GoPro Footage

I've been messing around with the GoPro video footage that I've taken during practices with different editing programs, including the one provided on the GoPro website and also CyberLink PowerDirector 11. The latter program is a little difficult to get into as I am still a novice when it comes to video editing but I'm starting to get the hang of how the program functions. I just can't figure out how to maintain high video quality after trimming down several clips and sticking them all together in one short video!