Welcome to the QuickBooks family. I can provide some clarification about the option you see in bills.
The Schedule Payment option is a new feature for users who wants to activate Online Bill Pay and process payments electronically. The ability to turn this functionality off is unavailable at the moment.
The option will only show to your transactions that still have balances. Since you're paying bills using checks, I suggest disregarding the feature.
For additional reference, you can use the following article to know more about entering bill payments in QuickBooks: Enter and pay bills.
Keep us posted if you need anything else regarding the process. Have a great day.