Changing Device that an Airport Express Extends

How does one change which device Airport Express extends? For some reason one of my 5 Airport devices is extending another one, or so it appears in Airport Utility. All of the Airport devices are connected to an Airport Time Capsule wirelessly (until I get Ethernet installed in house) and 4 of them are extending the Network wirelessly as shown by dotted lines in the attached screenshot. I don't understand why the one at the bottom left is associated with the one above it instead of the Airport Time Capsule I called TownLine like the rest of them. Any input from all of you would be greatly appreciated. I want to get this set up correctly on wireless before the Ethernet cables are installed since it may be a while before I can find someone to run the wires in my 1875 farmhouse! Should I just reset the one that's not cooperating? Thank you

P.S. Please correct me if I stated something wrong. I sort of know what I'm doing, just not how to express it,