After doing lumonsity exercises for a bunch of days I find that my speed/concentration scores are below 1000 (1000 is supposed to be average) while memory is at 1460 and problem solving at 1360.

When did you start, recently? I may be wrong but, I think average scores are matched to your peers regardless of time spent on the game. So if you just started exercises your score is being compared to everyone's score even those that have been learning how to play that particular game for a long time.