I installed that kernel but how do I try it? I tried sudo reboot -r and sudo reboot -r 5.15.0-83-generic but both tell reboot: invalid option -- "r" so should I follow the solution of the post How to get to the GRUB menu at boot-time??. I always prefer a simpler and safer way for these things instead of changing files manually like the solution at the above post, the 2 commands were supposed to make me try that kernel without changing the default one in use.