Change values on visuals using a list/dropdown

Hmmm, yes you should be able to create a disconnected table. Has to not be connected to anything else, no relationships. It might be called 'MyDisconnectedTable' and have an Item column with values of 

bunny

fluffy

poo

You should then be able to write a measure like this:

Measure =

  VAR __selected = SELECTEDVALUE('MyDisconnectedTable'[Item])

RETURN

  SWITCH(__selected,

    "bunny",SUM('Table'[Commission]),

   "fluffy",SUM('Table'[Revenue]),

   "poo",SUM('Table'[Cost]),

   BLANK()

  )

Not sure why you would not be able to get HASONEVALUE or SELECTEDVALUE to work. Please see this post regarding How to Get Your Question Answered Quickly: https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490

If you need additional examples:  https://community.powerbi.com/t5/Community-Blog/Solving-Attendance-with-the-Disconnected-Table-Trick/ba-p/279563