I'm assuming you're referring to the Bump app?? I don't know if there is a way to change your sn via the app. I did it on the desktop site on my ipad through TK.
Yes LizzyP posted earlier this week that she did it through TK as it's not available to do on TB yet. I would also imagine you may not be able to be mobile but not sure.
TTGPDecemberSiggyChallenge:FavoriteHolidayMovie: ~Santa Claus is Coming to Town~
TTC #1: July 2014 Me: 31 DH: 29
DX (me): Inborn error of metabolism - protein restriction, metabolic formula & weekly blood tests
DNA Results (7/1): DH is NOT a carrier for my genetic disorder!
7/3: Metabolic clinic gave the green light to TTC - holy crap!
Re: App help
~Santa Claus is Coming to Town~
Me: 31 DH: 29
DX (me): Inborn error of metabolism - protein restriction, metabolic formula & weekly blood tests
DNA Results (7/1): DH is NOT a carrier for my genetic disorder!
7/3: Metabolic clinic gave the green light to TTC - holy crap!