Budgeting tips when income drops

We are a household of 15 and the budget no longer works. I do not usually post, so bear with me. The rent is fixed and the car payment is high. Any apps or methods?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

A paper list of bills by due date helped me more than an app. I could see the month at a glance.