Reseting the forum format

Dont know how or why but the forum on my laptop is now in the mobile style . Hitting the full site button at the bottom does nothing nor logging in out .
Deleted all cookies and site data as well but still will only load in the mobile format.

Any ideas ?

I’m no tech but click on the icon at the top with three squares first then click on full site at the bottom. That what I do on my phone.
James