Moving Controls

Why do controls move of their own accord?
I have several textboxes in a groupbox their locations are set at design time, if I run the app or close the form and re-open it the text boxes are moving down the groupbox.
Generally the top value in the location increases by 1 or 2.
Any ideas?

Is the form size changing? Check their anchor points.

Anchored top, left
No resizing

Try locking them.

Form is locked

Undock them .

reduce ur grid size of the form to minimum