Restringir assinaturas apenas para admins e mods?

[JammyDodger]

I’m afraid that’s not possible, but there may be a workaround:

@JammyDodger

It’s currently not possible to limit the signatures to a certain group through the settings, though I think you could hide the input box for some groups using the CSS Classes for Current User’s Groups theme component [1] and a dash of CSS (though people could sidstep that using the browser tools,etc).