You may have to update your grub file in order to enable the custom resolution in the below file:
$sudo nano /etc/default/grub
Find and remove # from GRUB_GFXMODE line and replace with your required resolution, so it will look like this
GRUB_GFXMODE=1920x1080
Save and exit (Press Cltr+x ,y and enter).
Run below command and reboot.
$sudo update-grub
$sudo reboot
$sudo nano /etc/default/grub
Find and remove # from GRUB_GFXMODE line and replace with your required resolution, so it will look like this
GRUB_GFXMODE=1920x1080
Save and exit (Press Cltr+x ,y and enter).
Run below command and reboot.
$sudo update-grub
$sudo reboot
