I tried to change my grub file to select kernel 5.14.21, which is the 2nd one in the list:
GRUB_DEFAULT=1
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""
After doing sudo update-grub
, I rebooted the computer and the problem persists. How can manually set my default kernel?