Hello there, @GraceMary,
There isn't an option to override the amounts on the 941 form. QuickBooks Desktop complies with the IRS tax laws to generate the numbers based on the date you pay your employees.
If you need to adjust the amount reported on the form, you can use the liability adjustment feature in QuickBooks Desktop Payroll.
Please read through this article for the detailed steps: Adjust payroll liabilities.
Should you need anything else with filing your returns, just leave a comment below. I'd be glad to help.
You can override most numbers on the 941 and other forms by right-clicking the numbers and picking the option to override the amount. I think it is called "override" or similar (from memory.) This has always been the case since the inception of QB in the last century.
However, you don't need to and should not(!) override numbers to split a payroll that spans quarters. Payroll reporting does not work that way. Payroll amounts are always reported to the IRS, SSA, and all state agencies based on the paycheck (payroll) dates and not based on the pay period dates for the checks.