Print out your YNAB transaction list and your actual bank’s transaction list and cross off
Print out your YNAB transaction list and your actual bank’s transaction list and cross off and see which transaction is an outlier and doesn’t belong in YNAB. I printed out my bank statement and put a line through transactions as I checked them off which were accounted for. There was a discrepancy in the YNAB report. I entered a couple of transactions in YNAB that I actually paid with another method/cash that should not have been there. I think this was done in error at a time when it was late at night and I was fatiqued. The next day, I couldn't figure out the discrepancy and didn't want to waste too much time searching. So this crossing each one off on my print out works for me.
It was recommended by the support that once my accounts matched, I should reconcile. This is done by clicking on your account and then click on the Reconcile button in the top right. Then you'll be asked to confirm your current account balance. As long as it's correct, your account will be reconciled and green lock icons will appear next to your current transactions (as a reference point for all transactions that have been accounted for in that reconciliation. If your account balance didn't match, you'd be given the option to enter a Balance Adjustment to add the difference ( they don't suggest this for big differences) and that is why I like to find the discrepancy on my own.
This manual task of printing and crossing off may be avoided if I stay up to date and record my transactions as they happen.