Seems to me that thing has dip switches. Changing the code would involve changing the position of at least one switch and matching this with the dip switches in the opener and each of your remotes.

Don, all I saw was two wires coming out of the back of the plastic case. Will check again for dip switches but did not see any cover which could hide them. I suspected you needed to put in a 4-digit factory code of some sort then your new 4-digit code.