My university doesn't let me make any corrections to my PhD thesis manuscript after defending it because all the members of the jury signed that no corrections are necessary. Not even typos.
You must follow your university guidelines.
My supervisor is insisting I make the corrections we mentioned during my defense because he finds them necessary and to leave a few copies in the lab's library.
You should explain to your supervisor that the university has forbidden such changes. Presumably they are either unaware of the university's ruling or they know some exception.
However, since this is not technically allowed. I'm thinking of putting a disclaimer on the first page, something like: "This is a private copy".
You are free to make unofficial versions of your thesis available. Suitably marking such variants is advised to avoid confusion and a disclaimer is suitable for this purpose. Rather than This is a private copy, I suggest something more informative, e.g., The official version of this thesis is available from the university's library. This version differs from the original as follows: xxx.