Reply to default loop length in Traktor Pro

Can anyone tell me how to set the default loop size in Traktor Pro? At the moment it seems to be 4 but i'd like to set it to 16. I did RTFM, and the addendums, but couldn't find anything about this.

Basically i've mapped it so when i hit a button it sets in a loop and makes it active, and i have another to reduce loop size. what i'd like to do now is make sure it always starts at 16 bars when i hit the loop button.

Thanks in advance