There's a few things not on your side here:

1. At 114\900 you're probably dealing with a spherical mirror instead of a parabolic mirror. That's not actually a huge problem at your focal length. I have a 114\900 with sphericals and it delivers on image quality, but it is with bearing in mind.

2. Regarding collimation (calibration) if you have the funds, it's worth buying a laser collimator or a collimation cap (like an empty eyepiece with a crosshair built into it) to collimate your scope. A "quick and dirty" way to collimate would be to take the eyepiece out of the focuser and rack the focuser back so that when you look into the focus tube you should see your mirror and spider. You can then roughly align your mirror using the reflection of the spider as a crosshair. Once you can see the whole mirror with the spider central, you're good enough.

3. You mentioned that you can't see Jupiter's surface. Is this because it's too bright? Jupiter is a really big target so it bounces a ton of light at you. You can mitigate this by "offsetting" your view, like shift your head to the side a little bit, or if you're using a camera or phone cam, go into pro mode and tinker with your iso and exposure settings.

4. The images you see here aren't single shot images. The high detail planets and deep space images you see are the result of taking lots and lots of pictures and then stacking them together in software. Here's a copy paste about that:

Ok so from what I've learned so far for us phone photographers is that there's a bunch of software that's pointed at taking video and then pulling it apart and stacking each frame together into a single image, which you can then sharpen up and edit. A lot of this seems geared towards planetary imaging but I imagine you can apply some of it to deep space objects as you go:

The first thing you need is pipp. Pipp is for converting your MP4 video into avi files:

https://pipp.software.informer.com/

Once you've created your avi file, you can then run it through autostakkert to pull apart the frames and stack the images together:

Download:

https://www.autostakkert.com/wp/download/

Tutorial - https://m.youtube.com/watch?v=g67DfADSWvA&pp=ygUVYXV0b3N0YWtrZXJ0IHR1dG9yaWFs

And then once you've got your stacked image, you can then run it though registax or wavesharp. I've selected wavesharp because registax won't download from the website anymore:

https://github.com/CorBer/waveSharp

Tutorial -

https://m.youtube.com/watch?v=6FY8lTnsLkg&pp=ygUSd2F2ZXNoYXJwIHR1dG9yaWFs

And then once you've sharpened up your stacked image, then you can play with it in gimp or Photoshop. I chose gimp because I don't wanna pay for Photoshop.

Download:

https://www.gimp.org/downloads/

Tutorial -

https://youtu.be/Tl4Ie92MuTs?si=RWCYRxg5uZChtHqK

1. Your eyepieces are probably (if they're the ones that came with the scope) not the greatest quality. Thats not to say they won't do the job at first, but they're probably largely plasticky (sometimes even the lens itself is made of plastic) and uncomfortable to use. A few eyepieces from a budget brand like svbony can help here, or even a zoom eyepiece for convenience.

2. Your Barlow may suffer the same issues as point 5. It's important to note that you don't need to use a Barlow, especially using a 12.5mm eyepiece. Barlows work by effectively applying a "multiplier" to your entire focal length, which is how they give you more magnifying power. The issue here is that you sacrifice field of view, and the usually cheaply made bundle Barlows you get in the box with your scope aren't precise enough at the lens level to direct the light you can see properly, which can result in fuzzy images. Without a Barlow your mag through a 12.5mm eyepiece is going to be about 72x, with your Barlow it'll be mag multiplied by Barlow, so if you have a 2x it'll be 144x, 3x is 216x, etc. your maximum useful magnifying power on that scope is 228x, and you can get closer to that with a normal eyepiece at around 4-6mm while still keeping all the light your Barlow is sacrificing.

3. I have the same fork-mount for my refractor. That mount is horrendously wobbly. Only real cure for that is a different mount-head with a dovetail and tube rings, or maybe look at building a dobsonian mount from some old wood or chipboard. It's a fun project and a lot more stable.

4. That looks like a plastic focuser. These are going to be way more prone to flexing and distortion than a metal one, and that flexure will affect the quality of what you can see through the scope.

Overall you have a decent starter scope, but it has undeniable flaws that should've never made it to market, but the road to profit is paved with compromise. You could probably vastly improve your telescope simply by replacing the focuser and putting the whole thing on a Dobson mount, and then getting some nice eyepieces for it. Remember to stack your photos and familiarise yourself with wavesharp\registax and some editing software like gimp, Photoshop or lightroom.

Edits - so many autocorrects and typos

Don't buy anything else just yet.

The important thing is going out often the first weeks and months. Center marking the mirror can be useful, but your collimation can be way off with that mirror and focal ratio.

You should be able to see the brown belts on Jupiter with the 12mm, but probably not every time you are outside. Sometimes it's just a white blur with no surface details. The Jetstream moves a lot every day and can block the views like a waterfall.

You want Jupiter, Saturn, the Moon and whatever to be at least 20-30° above the horizon 40°+ is even better. You probably won't see the brown belts if Jupiter is 5-10° above the horizon.

You should be outside, don't look through a window from inside your house or apartment.

Let your telescope acclimate, cool down/warm up to ambient temperatures. It can take 30 minutes. This is important or you will not see anything sharp.

Saturn bad seeing, low in the horizon https://imgur.com/a/6ad9kHD

Saturn high in the horizon with good seeing. Saturn https://imgur.com/gallery/VhUwNIU

Jupiter & Shadow of Io (mid lower belt) https://imgur.com/gallery/f6i7ruV Remember the belts are low contrast at 150-200x.

These are all videos taken with my phone through a 114/900, probably at 150x

Perhaps you simply had poor transparency or seeing conditions. Those affect views far more that quality of gear.

Short answer - where are you observing from? Out in a field? Surrounded by hot buildings and asphalt? Observing out a window?

You need steady air to see detail on planets and you need to train your brain over several nights to understand what it is looking at.

Also try different magnification combos, every night is different, gotta hit the magnification sweet spot.

Understand that you will see detail that pops in and out of focus for a split second and you won't see Hubble images.

btw, the  12.5 eyepiece is the only on you have? I would suggest a 20mm and maybe a 6mm to give you a range of magnification.

The worst part of your telescope is the mount.

However based on your description you actually can find your target. In such a case you should be able to see "some" details on the Jupiter.

Using the 12.5mm eyepiece plus a 2x Barlow gives you 114x power. That is pretty high for your equipment (yes aperture matters but it is not only about the aperture), likely too high.

While collimation can be a factor, my gut feeling is that you don't need to worry about it right now.

Getting someone who has more experiences to show you all the little things you need to learn when observing probably is the best way to go. If that is not possible, I will say you should simply go out and use the telescope more often. Even with the same equipment planets don't always look the same. The atmosphere conditions (seeing) change. Their positions in the sky change (which will affect how they look), and the most important factor - your experience level changes. The more often you look at the same several planets you know what to look for better. And you will notice more details you didn't notice before.

Thank u, all !!! appreciate every your answers and advices, gonna try it as soon