Every fly line I've ever used had memory after being on the spool overnight.

On all but one of them (an off brand 'new design' clear mono line that I was asked to 'test") a simple stretching took the memory away. That applies to everything from Sharkskins to $9.99 reduced to $5 clearance lines I've found at WalMart.

If your line still has memory after you stretch it then I'd try changing lines. If you aren't stretching it every time out, that could be your problem.

Buddy