"Focus" there is talking about the Window that is focused {active}, I believe. IE - "When I change the active window, change that character to the main." But, you don't say what program you are using to multibox. ISBoxer should handle this on its own and you wouldn't want to touch that in Jamba, if I recall.

Jamba also has its' own slash commands that you can integrate into macros, such as the command /jamba-team iammaster <tag> and /jamba-team master <name> <tag>