Impossible to change permalinks

Hello there !
Well, i have a big issue on my website.

I have a 404 error on all my pages, except for my home page.
I tried to change the permalinks … and what a surprise, i can’t change it !
It stucks on :

I checked on my database, and here is the default value for my website :

it’s different from my settings and i can’t even change it from my database !

This issue is not present on all my other themes ….

Can i have some help / advices please? Thx