How to enable revision marks (underlines in color) in LibreOffice
You need to activate the Changes mode:
- open the document which you want to edit;
- go to ▸ ▸ ; and
- make sure ▸ ▸ is checked.
Start to make your changes. You will notice that all new text is displayed with a colored underline, while any text that you delete remains displayed but struck through in color. These options can be modified using the menu▸ ▸ ▸ .