Ok so I just downloaded it and wrote down my master seed, and was looking through the settings and the only thing that I would think would act as signing a message is where it says "export diagnostical data". Is that how you should sign a message through there? I haven't tried it just in case it would mess up anything.
No. I have tried Mycelium and Hive, they are the larger wallets and it seems like they do not allow the signing of the message. Coinbase does on their WebUI, perhaps you can try that. Sorry for the confusion, Mycelium android allows the signing of the message.