Sounds like you have it reset 'on start of layout' to lock any level > current level
Without seeing your code
You can create 2 Global Booleans
Level2Unlocked = false
Level3Unlocked = false
In your code:
where ever you unlock level 2, add in set Level2Unlocked = True
where ever you allow players to go to level 2 create event
Level2Unlocked = True > Level 2 Access (Copy paste whatever you currently have)
Rinse and repeat for Level3Unlocked