Reconciliation Problems

Last year I had to create a new Quicken file (at the direction of a Quicken Help person) because my old file was so big and wouldn't update correctly. That was for the 2020 transactions and after. I usually update the whole year when I get ready to do my taxes. So now for the 2021 transactions I'm having trouble reconciling with the last balance it shows. I think the wrong starting balance might have been put in in 2020, but I'm not sure. I use 2 files for 2 different accounts with the same bank. I download the transactions fairly frequently so I have those up to date. Occasionally I have to add one that was missed. The smaller file was reconciled for 2020 correctly, but when I started 2021 the beginning balance was off. I couldn't seem to get it corrected, so I used a balance adjustment figure. However, for the larger file, it shows 2020 not reconciled. I went back to my old file and apparently reconciled it for 2020. I tried going back to my 2020 statements and reconcile the new file, but the balance and my statement and the file don't match again. I had started to reconcile it and canceled it several times and now it's all screwed up. I'm not sure where to go from here? I primarily want to get 2021 reconciled to my bank statements so I can do my taxes for last year. HELP?