Hi there my scheme looks like this
This black scheme on the left side, this is type of connection that i use for my "potentiometer" . This is thing from USSR , and it's like potentiometer with 10 fixed positions , in my build i use only 7 . But i didn't find scheme with 7 buttons (It works like 7 buttons) , only 4 buttons , but you just imagine other 3 buttons and resistors.