I ran into this same issue today - realized that the last several months of payroll were processed through a new bank account correctly but were being linked to the old account in QBO. Could not find a way to re-link or move the transactions to the correct QBO account.

After fixing the settings for the future, I ended up creating 1 transfer from the old account to the new account in the exact amount and on the exact date of each incorrect transaction. That took care of the issue.