There are several times where changing your locks, or rekeying may be advisory. Obviously the number one reason to change locks is when you move in to a new appartment. Whether you are renting or buying, and regardless of how trustworthy the previous owner appears. Rekeying your locks is a good choice. Even if you are renting or buying from someone you trust 100% they are not the danger. The danger is that they may have lended a key to a third party; let a friend of a friend stay over, leave a copy for the friendly forgetful neighbor, lost a few copies, had a key stolen long ago along with their wallet and so on. Changing the locks will definitely significantly decrease your risk of a home invasion / break in.
Another instance in which you may consider changing your locks is if you yourself have lost the key. Doesnt matter that it probably just fell on the street and someone who finds it wouldnt know where you live. It is just as likely that it was deliberately lifted from your pocket for the sole purpose of getting into your house.
Yet another case, and by far not the most pleasant, is a conflict with a spouse or a partner. If it is your house, and you want them out, Change the Lock! Yes, they do have the key, yes they will use it if they want to get in. Most of our locksmiths calls regarding locks change and rekeying happen AFTER an Ex boyfriend or girlfriend have reaked havoc on someone appartmant. Just as often, we get calls AFTER a breakin had already occured. Remember you can prevent it!
There are other reasons to change your locks, but the ones mentioned above are the main ones. You will have to call a locksmith far less ofter if you follow these guidelines. In any case, Edwards Bros Locksmith Pittsburgh is ever at your service!