If your address keeps changing every time you make a transfer that means that your wallet provider is, most likely, using an HD (hierarchical deterministic) wallet, which changes transfer addresses after each use. Please confirm this with their customer support.
Other old addresses should remain unchangeable but you should verify this information with your wallet provider, since we are not familiar with the functionality of other services.
Alternatively, you could make a $1 test withdrawal and see if the old address works.