1. Tell your landlord about the problem

Landlords are responsible for safety and security as part of proper maintenance. If a lock to your unit or to the common areas is not working properly or is not strong enough, your landlord must repair or replace it. If previous tenants or employees still have keys, the landlord should change the lock.

Your landlord might agree to let you get a new lock if you give them a key right away. You should get the landlord's agreement in writing before you go ahead.

In this case, the landlord should pay you back for the cost of changing the lock. It's a good idea to keep any receipts to show your landlord how much it cost to buy the new lock and have it installed.

If the reason you want to change the lock is not something the landlord is responsible for, you might have to pay for it yourself. For example, you gave a key to someone that you no longer trust, or you broke the lock yourself. You still must get your landlord's permission to change the lock and give them a new key.