Self confidence does not come from constant praise, it comes from a child feeling capable of handling challenges and carrying the results of their own choices.
Instead of a general phrase like you are so smart, try describing the effort, I noticed you tried many times until you figured it out. This teaches the child that their worth lies in the effort itself, not only in the outcome.
Allowing a child to make small mistakes and work through them on their own is far more powerful than perfect intervention, because confidence is built through experience, not through perfection.
This week, choose one situation and let your child work it out on their own, even if the result is not perfect.