To say I've removed dozens of those would be lying in understatement.

Match the bit to the slot as closely as you can. Tighten them first to break the paint, then loosen.

Get a screwdriver slightly too large and a small single cut mill file and file it down to a perfect fit. As Ron said barely tighten then remove. In the unlikely event it still does not come out apply a few drops of Kano Kroil penetrant and let it sit overnight, it is one of the few products that actually does work "better than everything else".

I use a Brownnells Magna-Tip Set for all of my reel work. Surly not the cheapest option out there, but they offer flat blades in 9 different widths from .120" to .360", each with four to six blade thicknesses from .030" through .070" in .005" or .010" increments.

Question:

Are the screw slots on all Young reel feet the same?

If so, I can see what bit fits the only Young I own, a smooth finish Pridex with a three screw foot and tell Shrimpman the Brownells bit that fits. That will reveal the size of the Brownells bit you need, or at minimum be the blade size you need in another brand.

All things being equal, a Brownells Magna-Tip 180-3 (Part # 080-180-330WB) bit fits the reel foot screws on my Pridex perfectly.

That bit is .180" wide X .030" thick and costs $3.99.