How to push changes from one years tax returns to the next

I finished up 2 consecutive years of tax returns earlier this week.  I didn't file them yet.  (I didn't owe taxes b/c I'm a landlord running a loss).  I've been doing some research and I'd like to make some changes to year 1's taxes.  How can I propagate changes in year 1 into year 2?  I don't want to restart year 2.

 

Thanks