GUI resolutions problems

Question

I have been creating a GUI application in C#. As I place controls on each form and view the application on different resolutions, the controls become distorted. Other articles recommend docking and anchoring, but I'm not sure how that fixes the problem. It seems that docking and anchoring simply keeps controls relative to the top, bottom, right, or left of the form. For instance, I might add a label and text box. Viewing on a different resolution causes the label and text box to overlap. This problem still happens when I anchor the controls. I am having a hard time getting my head around how docking and anchoring is supposed to solve the problem. I have done some relative positioning by grabbing the parent control size and calculating the child sizes and spacing using calculated percentages which works fine, but is very time consuming. Any recommendations would be appreciated. Another related question is how a developer tests their GUI app on different resolutions? Is there a tool for such? Thanks