First, you should never open a Manager accounting file that has been used by a newer version with an older version of the program. All new program versions can access and update as necessary older data files, but not the other way around. So be careful what you do. Not every update, but some necessarily modify the data structure. You can end up with very serious problems.
The separate Cash Accounts and Bank Accounts tabs were consolidated many months ago. All are now under Cash Accounts. But former bank accounts should be available in the Cash Accounts tab.
Read the guide about updating on Mac:
Once you’ve installed the update, import using the the last “good” backup file. That means one that has not been opened and closed by various versions of the program on miscellaneous platforms. Based on your bank account issue, you had quite an old version, so you will not have date codes in the file names of your backups. You’ll have to use Get Info to see when they were created.