Hello!
Grub Customizer will let you change the default OS, change fonts (careful!), add an image to GRUB screen, and more. I add it every time I install a Linux OS.
NOTE: If you use boot-repair to fix a broken bootloader, it uninstalls Grub Customizer. As a result, you'll have to reinstall it after your boot is fixed...
73 DE N4RPS
Rob