If I give the bot my new BTC address of my new CoPay single-address-wallet, it asks me to sign the message - I can't. CoPay doesn't support signing messages.
Is there any Android or Ubuntu wallet that supports single-address-wallets and can sign messages?
What are you guys using?

EDIT: Now I send my Byteball address to the bot (as you said). Now I can verify the new single-address-wallet by paying the small amount. Great.
But I don't need to sign the message, right? Send the amount is enough?

Edit 2: it worked. only had to send the amount. now my old bytebaöö address is linked with new single-address-wallet. thank you!