Did you reboot after you changed nvidia drivers through 'Software & Updates' and ubuntu-drivers command?

" Ubuntu(19.04) uses an integrated one instead of nvidia card" and you have that one disabled in BIOS perhaps?

@sudodus Every time I change something I rebooted

@Rinzwind I didn't change anything in BIOS but secure boot Moreover command nvidia-smi shows that nvidia card uses 2 MiB of it's memory

Hopefully you disabled Secure Boot...

@GabrielaGarcia yes I did

What does the command prime-select query show? If it shows intel run it again as prime-select nvidia then reboot.

@Terrance it shows 'nvidia'

That shows that it is set to use the NVIDIA card. What is the output then of nvidia-smi?

@Terrance well it shows information about video card and at the top it shows 'Driver Version: 430.14'

That is using the NVIDIA card then.

@Terrance but settings shows that ubuntu isn't using nvidia card and games are very laggy

Also, make sure your monitor is plugged into the GTX 1050 and not the one on the board. You might have to disable the onboard VGA in your BIOS as well.

@Terrance I use laptop

OK your question is worded poorly then. As it sounds like you added a video card to the system. In Linux just because you have a high performance card that does not mean that it is going to run well. There are many factors as to why you get lag. You might need to look for tweaks to the desktop, etc. There are many different desktops that have different tweaks to help speed things up. Like in Xfce4 replacing the WM with Compton instead of the one built in. GNOME might need a tweak tool, etc.

@Terrance 3 reason why I think that ubuntu does not use nvidia card: 1) Settings of gnome shows "Intel® UHD Graphics 630 (Coffeelake 3x8 GT2)" instead of nvidia. 2) nvidia-smi shows that only 2 MiB is used of 4GB. I don't think that gnome is such a lightweight environment. 3) The Witcher 2 that was released in 2011 is very very laggy on lowest settings. Do you still think that ubuntu uses nvidia card?

Knowing this was a laptop is paramount! We also don't know what is your iGPU- Intel or AMD? Don't skimp on relevant details please! -- Since this is a laptop it is considered a 'hybrid graphics' system. I'm not sure that you can disable one or the other completely but this question may help.

@0442A403 Yes, but you need to edit your question and please add in all details, like Nmath above has stated do not skimp on relevant details. Also, I will no longer be of help from this point as all my experience shows it it using NVIDIA, but since I CANNOT duplicate your environment I will be of no use. Sorry.

At login click on gear and select a non wayland choice. Wayland doesnt use the nvidia hardware.

@Nmath I add laptop model and processor model. I don't know what to add. If you need anything please ask.

@Terrance ok. Thanks.

@ubfan1 I haven't used Wayland, I use 'ubuntu' environment.

What makes you think your laptop has 'integrated' graphics other than the nvidia? What makes you think you are not already using the correct drivers?

@rtaft please read my comment above that begins with '3 reason why I think that ubuntu does not use nvidia card'. Moreover ubfan1 said that Wayland does not use nvidia but it works on the laptop.

@0442A403 I'm with you. There's something wrong with the drivers. I suggest reinstalling but make sure you use the latest version for that GTX1050, i.e., 430.xx. If not available in Additional Drivers then add the graphics drivers PPA.

@GabrielaGarcia I have chosen 430.xx(but it wasn't last version) driver in Additional Drivers and it didn't work then I tried to install driver from ppa also didn't work. After that I decided to install

After that I decided to install drivers through a file from nvidia site. So I executed a file and after sometime it showed a error. And now I can not to loggin in profile(it's just freezing) and I can not use ctrl+alt+f3 cause some strange lines just appear and if I write a command nothing happens but if I press ctrl+c after command with sudo it ask a password but after a password input nothing happens.

I'm really not an experienced user but it seems like ubuntu tries to initialize nvidia card but it can't

Oh I forgot. That error from nvidia's file showed next "unable to load the 'nvidia-drm' kerbel module" and below it showed "[477.394376] PKCS#7 signature not signed with a trusted key".

I just spoted that if I wait a while after a boot then I can login to profile but it shows just a purple screen and I can just move a cursor. Also if I try to change VT after that time then laptop freezes.

I have already faced that problem just after I bought the laptop. I fixed that with guide which says reach the grub selection menu by pressing esc and edit something in boot option but now I can not reach that menu if I press esc.

Well I don't exactly know how but I after holding right shift and pressing esc I logined to profile and installed drivers through sudo ubuntu-drivers autoinstall. So now ubuntu still doesn't use nvidia card.