if you use dark-mode, the default red can be hard to see
posted: 2026-01-06

i couldn’t find up to date instructions when i wanted to change this so here you go:
tools > options > libreoffice > appearance > customizations
in the first dropdown choose “spelling mistakes” and then choose a color you want in the second box

this was written referencing version 25.8.4.2 - libreoffice community edition