It’s not clear if you are an owner or renter? But regardless, in most large apartment buildings the front Unit doors are the property of the Owners Corporation (being fire doors). However, while the OC owns the door, the owner owns the locking mechanism, and can re-key the locks. However, you need to check the building’s by-laws, in case there is something special about the locks in that building? If you are renting, then contact your agent, and notify them that you believe the security of the Unit is compromised, and ask them to change the lock, (or you could offer to pay for that?).
Also, generic keys and locks are unusual, for an 80 Unit block. How do you know that? Double check. If that neighbour has a key to your Unit, it’s possible a previous resident gave them a key (in case of being locked out, say), and they may not have returned it.