Rooms and tenancies
Add each house and its rooms, then add a tenancy to each room you let. Every tenancy has its own rent, so you always know what each room should bring in.
What's due and what's overdue
See the rent that's due and anything overdue, room by room and tenant by tenant. When a payment comes in, record it as a bank transfer, cash or another method.
One account for each tenant
Each tenant has one account, even if they rent more than one room. When a tenant moves to another room, their account goes with them, so there's nothing to type again.
From move-in to move-out
Keep the tenancy agreement and the deposit with each tenancy. Record rent increases, notice and the end of a tenancy in the same place. A tenant who is moving in later shows as "moving in" until their tenancy starts.
Room history and inventories
Every room keeps its history: each past tenancy, who it was and when. Record what's in the room, then a start of tenancy and an end of tenancy inventory with photos. Each new inventory starts from the latest one, so you only change what's different.
The rest of the house
Split shared bills between the rooms, keep the house's expenses together, and track issues and repairs that tenants report.