Reward History speaks to the amount and quality of reinforcement that has happened on a behavior in the past.
Having a good Reward History on a behavior means that the dog likes to do it, and has plenty of reason to do it. Reward history creates a desire to perform the behavior.
Tricks that you struggle with probably do not have a strong Reward History on them.
Don’t skimp on reinforcement, the more Cookies given the more potential Reward History you have to leverage.