Hi, I'm a complete Krita beginner. I've searched the forum but havn't seen any post on this issue: I'm following the Krita tutorials, but the recommended shortcut for making a real circle instead of an ellipse doesn't work. I'm currently using Krita on MacOS with the Wacom Intuos S. Does anybody have an idea, what the reason could be? Thank you!

I assume that by, "...the recommended shortcut...", you mean pressing and holding the Shift key. (Note: it's not a 'shorctut', it's a 'modifier'. Keyboard shortcuts are a different thing.)

It may be that you're pressing the Shift key before clicking your mouse left button and dragging, If so, you need to wait until the ellipse has been started and dragged out before you press the Shift key. Similarly, use of the Ctrl and Alt keys as modifiers needs to wait until the ellipse has started to be drawn.

If none of the above helps, please provide more detail of what you're doing and what's happening. You may need to wait for someone with MacOS experience if it's an unusual problem.

Thank you, ahabgreybeard, it was indeed a timing issue: As you wrote, first pen, then the Shift key, and then remove the pen still pressing Shift key. This works! Thank you very much for your quick help!