Spell check not working in reply.

Using Office 2010 and Windows 1903.

When replying to an email spelling errors comes up underlined. A right click instead of offering the correct work comes up with signatures.

Now the perceived wisdom seems to be that you edit signatures and put -- above the signature and when replying type above the --. I find this doesn't work.

If you use review then yes the spell checker works but I would quiet like the right click method to work.

Any ideas?

(Have had this problem for 10 years).