Can I change my date of birth on my profile? I didn't catch it when I used the app last year, how can I correct it on my profile this year?

What is your birth year (1967, maybe?)  You might have to amend 2016, since some deductions and credits are age-specific.

Make the birth date correction under My Info section. Select the 3 horizontal bars in the upper left part of your screen if you don't see it.