What do you mean by "keying screens using FF"?
Firefox uses extensions for spell checking, it is completely independent of any word processor that is installed.
Note that the AOO files however can be used for FF spell check.
If the trouble is with your Writer installation that lacks spell checking, see at the top of the Writer forum, there is a tutorial to fix it.
Please add '[Solved]' at beginning of your
first post title (
edit button) if your issue has been fixed.
LibreOffice 7.0.3 on Xubuntu 20.10 and LibreOffice 6.4.6 (portable) on Windows 10.