Can't Change To Nvidia Proprietary Driver Ubuntu 18.04

Solution 1:

Try to remove the installed drivers by running:

sudo apt-get purge nvidia*  
sudo apt remove nvidia-*  
sudo apt autoremove  

Check what is the recommended driver for your Nvidia card by running:

ubuntu-drivers devices

If you want to install the driver automatically, run :

sudo ubuntu-drivers autoinstall

If you want to install a specific driver, run:

sudo apt install nvidia-<driver number>

Once the installation is finished, run prime-select query to check which graphic card is being used by your device.
If you want to change the graphic card used by your PC, run : sudo prime-select <intel/ nvidia>; choose between Nvidia and Intel graphic cards.
After that, restart your PC to apply changes