After I click into the slot that says create user, is there a way to delete or reset it so I can start again from the beginning? After filling up all 3 slots, I can't make any full runs anymore. :(

I know this is a noob question, but how do I get back there?

The videos in the guides won't play for me. Just wondering if it is my computer's problem or is it that it just won't work. If it doesn't work, can the creator of the guides try to fix it?