Minecraft Full screen resolution problem?

Okay, so after i solved my problem with the game (the launcher did not open) i got another problem. So I reinstalled completely the game, but this time the screen resolution is different. In order to show you the problems look at the photo.
On the top you can see how the game looks for me when i open it with fullscreen: on.
In order to show you the problem i turned off fullscreen.
When I click on Maximizing window (bottom photo) this is how my game used to look before and how i actually want it to be.
I went through the launcher settings and i managed to change the resolution, but as you can see the only result is happening when the game is not in fullscreen with maximized windows.
I tried to click FullScreen when the windows is maximized, but the resolution changes back to the top one.
I want the bottom photo resolution on fullscreen ON!
Hope you understood my problem and help me solve it.Minecraft Full screen resolution problem

Didn't fully understand your explanation, are you talking about the size of the UI? Or are you talking about the taskbar (Bar on the bottom with Start Menu, Chrome, Spotify) being in the way of your game?

All you have to do is go into Options > Video Settings > Fullscreen and your done. It's worked all the time for me.