How can I change access permissions across many pages?

Not right now. In the next version of WordPress there will be custom bulk actions, then it’ll become easier to do.

Maybe for now you can use this plugin https://wordpress.org/plugins/custom-bulk-actions/. Unfortunately that’ll require some coding on your part.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)