I did not find the option within the app to change the passcode after setting up the smart lock
Which pass code are you looking to change? Each individual chooses their own pass code and can be changed by opening the security app, click on the smart lock picture, click on Manage access, choose whatever name you want to change the passcode for and change it then save it
Just to add a few more steps.
Choose the name u want to change then tap Passcode and It will direct u to the passcode screen.
Once u r in. Tap the passcode section and the number keypad will appear.
Use the backward button on the bottom right hand corner to erase whatever number u don’t want.
Update the new passcode then tap the Change Passcode button. That’s it.