Monthly rent
Change the rent from a month you pick. Earlier bills stay as they were.
Open the tenant from Tenants. On a computer their actions are in the side panel; on a phone, tap ⋯ on their page. Earlier bills never change.
Tap Edit or renew, then Monthly rent.

Pick the month under Starting with and type the New rent, each month.
Say What changed (your tenant sees it), and attach the signed addendum if you have one.
Tap Save the new rent.

What you'll see
Every bill from that month uses the new rent, until you change it again. The tenant's Lease page lists it.
Next
Add a pet
Can't find it? Ask Moolah in the app, or write to hello@thepropertyledger.app.