I filed my taxes with you guys, and chose to print it out to send to the IRS. I change my mind, how can I change it to do it online with my 1040 from 2017?

What do you mean with 2017?  Do you need to file 2017 also?  You have to file each year separately and 2017 can only be printed and mailed now.

How to change from Mail to Efile <a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/replies/5561257">https://ttlc.intuit.com/replies/5561257</a>  

you can't e-file 2017.  

if you mean 2018 and have mailed in your return,   then go to IRS website to see if they have transcript.