Ok, everyone who thinks Kreds are bad on this game (not talking about other games) is kinda wrong. This game only has Kreds because this is a Mochi game. Since Mochi games are banned from this site, they improvised Kreds into the system.
I found a glitch, if you finish a level and you didn't get the required points, wait until the upgrade box disappears after a few seconds, then push restart. You will be sent to the next level.