The best glue to re-adhear just a corner or side of your screen is two part expoxy (Alraldite) the quck 5 min set one is the only one to use.

I do phone repairs and use this reguarly. Its the best method available for lack of something better.

Ultimatly removing the screen, removing all the old adhessive and reapplying the proper manufactured adhessive gasket cut sheet is best,

But for a quick job that works well use Alraldite.

Mix and apply with a tooth pick and use sparingly.

Using Aralidite the screen can still be easilly removed in the future if it requires replacing.

Note:Superglue is not recommended for use adhearing glass. (The instructions will state that) Its a bad choice. Also super glue will break apart from one minor drop.