You can change codes as often as you like, for use by babysitters, contractors, etc. You can also reset the lock so you can reset the master code, which is needed in order to set the other user codes.
Rather than re-type all the step-by-step instructions, since you also could benefit by having a copy of the manual for your use and reference, I'll give you a link to a free copy you can save and print.
http://www.smarthomeusa.com/Products/ED1460XXXX/manuals/WeiserLockPowerbolt1000-manual.pdf
Hope you find this Very Helpful and best regards!