1. Go to the Room tab on the left
2. Go to “$ Bulk Room Rates” at the top right hand corner. Press it.
3. Press “+ Create New"
4. Chose a property and fill in ALL the fields. Make sure the “VALID FROM” is correct and is the first day of the new Market Rent is correct. 
5. Then press “Save".
6.  Then go to some individual rooms for that property and make sure the rent increase has worked.