Hi GamesPWND!
Happy to explain! I know it's a little tricky, so I'm glad you've asked for clarification!
Let's say you want to use the audio from Clip A (guitar players) but the visual from Clip B. First steps are to add both clips to your timeline and expand track controls using the button highlighted with a green square.

Click and drag your visual up to the second track! Leave your clip with the audio on the first track.

Now you have some options. 1) Drag clip B over clip A to replace the visual. 2) Disable the visual on the first track using the "eye" icon. WARNING: This disables video for the WHOLE TRACK! Not just that one particular clip.

Does this clarify the process? I think you'll also be pleased to know that we're simplifying this process in a future update. Thanks so much! Let me know if I can help further.
Caroline