I'm working on a video I'm editing and I've come across a small issue which probably have more to do with my lack of experience rather than the program itself.

Say I have a layer with a video background (let's call it "a"). Then I want to add a smaller (in size) video on top of it (picture in picture, right?), let's call it b. What I'm finding difficult is to make sure that b´s size is imported at exactly 100% of its size. It seems that I can only adjust its size manually, and the video is imported at a size well over 100%, to fit the size of the background, but that's a big issue for me because then I can't seem to be able to readjust b´s size to its genuine 100% size. PD17 Ult, PD16Ult, PD15ult + 13ult + 12ult
Painthop X9, X7, X4, 9
Aurora 3D (!!)
Animation Shop
Flex Gif Animator
Howler 9.5 !!
Intel Core I7-479 Cpu, 3.6 Ghz, 24 Gig Ram
Windows 10. 64 bits