As far as I know, GRUB boots by default the latest kernel, the one with the
highest version. The GRUB_DEFAULT variable, in /etc/default/grub, can change
that behavior:
https://www.gnu.org/software/grub/manual/grub/html_node/Simple-configuration.html
(if you modify that file, you then need to execute 'sudo update-grub' for the
changes to be taken into consideration).
The other kernels can be booted from the "Advanced options for Trisquel
GNU/Linux", in GRUB's menu.
Use a kernel that properly drives your hardware.