Don’t know what my phone password is so I can update software

You don't know your passcode?

See the Apple Support article(s) below. 

Passcode - If you forgot the passcode for your iPhone or your device is disabled.    *

Or your Apple ID password? If you forgot the Apple ID (iCloud) password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage  -     

Apple ID – Forgot Password  *      

If you forgot your passcode, you can reset the device: https://support.apple.com/en-us/HT204306