Hi. this is my first year using turbo tax. i think i may have made a mistake in prior years returns I did by mail.......can i refile them

Welcome to TurboTax! Yes, you can "re-file" prior year returns by completing an amendment. First you would need to make sure that you have a copy of each years return that you would like to amend in order to complete the process. Then see the link below for more information on completing amendments: https://ttlc.intuit.com/replies/3288565