I found that in 2016 I entered my DOB as 03-07-1959 instead of 07-03-1959. How can affect my 2017 return. What I need to do?

Did your 2016 return go through or was it rejected?  Do you still need to file 2016?

It wasn’t rejected. I’ve already received a refund

You really don't need to do anything related to your 2016 return. Just make sure to use the correct date of birth going forward.