I can share some information about how online banking works in QuickBooks Self-Employed.
When you connect your bank or credit card accounts, QuickBooks Self-Employed only downloads the last 90 days (or more depends on your bank) of transactions from your financial institution. Additionally, the program automatically downloads new transactions from your connected accounts every time you sign in.
If you need to get older transactions from your bank, you'll have to manually upload them via CSV file. You can start by going to your bank's website and follow the on-screen instructions on how to download them. Once done, please follow these simple steps to import the transactions:
Go to the Gear icon, then choose Imports.
Select Import older transactions for the account you want to add transactions to.
Click Browse and find the file you downloaded from your bank.
Select the file, then click Open to start the import.
Review the column headers and data, then make sure that the date, description, and amount columns on the CSV match the columns and order in QuickBooks.