Why are multiple bills combined on one check?
If you have a vendor for whom all selected bills are being paid with one check, and you would prefer separate checks for each bill, you must update the Vendors → 1099/Checks. There is an option to always print a separate check for each bill. If that is not marked, all the selected bills for that vendor will be printed on one check. See the help article How do I set up a vendor to print only one check per bill?