Unable to change email to my meta account

I accidentally posted this in the ai glasses forum so I'm re-uploading it

I have an old yahoo email that I've been trying to change to my new Gmail email and every time I try to replace or add the new email to my account it says it already in use. I've been at this for hours now and can't seem to get any further than that

Attempt to replace the email

Attempt to add the new email from my Facebook to my meta account