How to remove a very tight screw from drywall?

[Innov8tive]

I have tried everything I can with all my tools to remove these screws. Spanners, screwdrivers, adjustable spanner and reverse drill. They are very tight in the drywall. Unfortunately people that did repairs just didn't do any of the jobs properly so there's been a lot of hassles. I simply don't have enough leverage or force with any of my tools to get this out. Alot of things are fixed to plasterboard walls.  I'm having this issue with alot if things round the house so looking for something that will definitely work for tight screws and ones that have been screwed in on the wrong angles. 

[Innov8tive]

Totally another option @Noyade.

I think though I got to remember my budget. Doing a whole house Reno means my spending needs to be justified at this point.