From a pure scoring perspective, FICO 8 really likes it when you have an open loan with a small positive current balance compared to the original loan amount.
In your case it sounds like this "overdraft" is reporting as a loan, so be sure to look at your credit reports and see how it is conceptualizing the "original loan amount" -- probably it is doing this based on the maximum amount your OD can be. You want your current loan balance / original loan amount to be < 8.99% (assuming you have no other loans).
Before you get too happy about this, be sure you understand the financial implications of it. If your checking account is constantly overdrawn, does the bank not like that? Is it possible that they could close the account? How much does it cost you to have a $5 overdraft each month?
The scoring point penalty between no open loans with a positive balance vs. at least one loan with a small positive balance is about 30 points. You could simply live with the penalty most months and then in the 40 days before an important app for credit overdraw your account and get the boost.
Likewise FICO really likes it when you have one card with a positive balance. It dislikes it when ALL your cards have a positive balance. Unfortunately, because you only have one card, you have to choose between the two, and the best choice is to let your card report a positive balance. In the medium term, however, you should be looking to add a few more cards so you can have one card with a balance and the others at zero.
