Hi Wang,
you can change distribution channer using mass, but before that u should create in SPRO.
Tcode: MASS >select objcet -BUS001001 then select table or field > if not able to find u can search here>after click on selection field >click F8> then input new value in change field distribution.
I hope will work.
Further any qyery pls ask.
Regards
Sanjeet Kumar