open the chart of accounts from the gear menu
find the bank account and use the selector arrow far right Run report
set the date range
at the top right of the report is an export icon
If you want every transaction regardless of the account source, then log in as the accountant user and export the general journal for the date range you are interested in.
QBO data handling capability for reporting is not adequate, if there is more than 5K records it times out and reports that you have too much data. You will have to do a journal report in date range segments, like Jan-Feb, Mar-Apr, etc etc.
How many months you can span per report is a guessing game since the report can not deal with more than 5K transactions.