Hi @Rach123456,

That notice is likely something youri nstitution added to the grades page themselves, as I don't recall ever seeing a notice like that in our Canvas and the link included goes to an institution help page.  You way want to reach out to your institution's local Canvas team with your request, as they should be able to change the width if I'm correct it being a custom notification (there will also be nothing Instructure can do about it in that case either).

I hope this info helps!

-Chris