To change UnitFrame texts or icons, go to this menu:
/ec
→ UnitFrames → Individual Units/Group Units → Select which Unit → Custom TextsSelect which text: !Name, !Health, !ClassIcon
Customize the settings or the format
Check out this ElvUI entry for a full tutorial on Custom Texts: https://github.com/tukui-org/ElvUI/wiki/custom-texts
Check out ElvUI's Available Tags section to find out what tags you can use in your text format!