Make Holes for Screwheads

[br51095 (Beni)]

Hello Guys
I’m new to blender and am mainly using it to create models for 3D printing.
In the Picture below, you can sie my latest project. i created a hole to fit a screw. Now i would like to make the upper 4mm part of tho hole slightly bigger tho fit the head of the screw inside.

I tried out some stuff but only came up with the idea of making a loopcut and scale the selected part. But i don’t want it to affect the lower part of the hole.
I hope i unterstand what i mean

[RickyBlender]

one way would be to add a edge loop inside the hole
then select the top loop and scale it

another way select top loop and add a bevel with Ctrl-B

happy bl

[br51095 (Beni)]

Thank you very much, that helps a lot!