Hi Wayne,
There is no fast way to do this in bulk segment-wise if you have 15 different request setups each with different segments. You will have to go in and edit each one and click the Mobile device segment checkbox so that it ANDS logic wise in segment filter logic with you existing segment.
An alternate option that opened up with Virtual Report Suites is you could make a new Mobile Device virtual report suite and then your same existing segments could be applied as is. This allows you to skip having to editing each segment logic per request since the Virtual report suite governs the mobile data filter. You can switch the report suite in bulk for all requests assuming it is the same report suite in play for the entire worksheet.
Best,
Brian