The ability to run the Bank Register Report (Under Reports > Banking/Budgeting > Bank Register) for multiple/all Bank Accounts is not yet available. This is being tracked under Enhancement # 165077.
As alternate solutions, customer may consider below:
1. Navigate to Reports > Banking/Budgeting > Cash Statement.
-This report will show the balances for all Bank Accounts.
-Click the View Detail link as desired.
2. Navigate to Reports > Financial > Balance Sheet > Detail.
-Click on Customize button.
-Click on Filters link.
-Under Budget and Financial folder > Account (Line) folder > Click on Account Type field > Filter: equal to Bank > Hit Done | Show in Footer = Yes.
-Hit Save or Preview.