I think you got some bad information. The Desktop program should be a lot easier to use. Were you able to transfer from you 2019 Online return? We could have told you how.
Then it sounds like you need to update the program. The Desktop program needs to be updated frequently. Updates usually come out each Thursday. If your program is not automatically updating each time to launch it (or are you leaving it open?) you need to go up to Online-Check for Updates. Are you on Windows or Mac?
And be sure to save your tax return frequently too. Go to File-Save. It saves it as a data file ending in .tax2020 usually in your Documents. Then when you are done also save it as a PDF file.
Then for your AGI reject. When did you file 2019? If it was late in the year or you mailed it, try putting in 0 (zero) for the AGI. And see, https://ttlc.intuit.com/community/rejections/help/what-if-i-entered-the-correct-agi-and-i-m-still-ge...
How to correct the AGI
https://ttlc.intuit.com/community/agi/help/where-do-i-correct-my-agi-in-turbotax-online/00/26311
