Safari auto fill in other forms grey out can’t use it

Dear folks,

I use Safari on my MacBook with the newest Tahoe version instead of Chrome. Now a weird issue in Safari comes up. In Chrome I always uses auto fill in the forms, so not only for passwords and names even for simple details like typing 123 in a form and next time click on it it appears again in the box.

So I checked other forms in settings in Safari and the box greyed out also only a purple header around it. So I can’t even use it. Same if I click right in the option tab box shows up with contacts/passwords/creditcards but no other forms option.

Why is this option not there, I read something about delete the plist forms file of safari but how? Or is there another solution?