Welcome to the Community. I'd be happy to help share some information about adjusting the timesheet set up in QuickBooks Online (QBO).
There are two types of time sheets available in QuickBooks, the weekly and single time sheets. Currently, the option to modify them and use a bimonthly format is unavailable.
What we can do is to integrate a third-party application to QBO. You can browse our different options for third-party apps from the Apps Center. Just click Apps from the left navigation panel on your QuickBooks Online homepage or go to Apps.intuit.com. If you can't find what you need, you can try searching the web.
I've attached some links below for future reference:
That should get you back on track. Please know that the Community has your back if you need assistance time tracker or about QBO. I'll be happy to help you some more. Wishing you and your business continued success.