In most cases there isn't any inGame config. You'll have to edit the .lua file.
You can find the file in the AddOn folder of the AddOn, generally
<WoW folder>\Interface\AddOns\<AddOn>\<AddOn>.lua or
<WoW folder>\Interface\AddOns\<AddOn>\config.lua
Open it with an editor (I recommend Notepad++) and edit the values in the described area.