But Bither didn't prompt for "Switching to cold wallet".
check your wallet seed for your old wallet "hot wallet," make sure that you have saved it correctly (Keep it in pieces of paper or anywhere safe,) delete the wallet data (Settings --> General ---> iPhone or iPad Storage ----> Delete App) switch-off (offline,) open Bither.
In short, the wallet needs to be empty or an address has not been created.
AFAIK, you can’t back to hot wallet mode.
source --->
https://bitcointalk.org/index.php?topic=5149848.msg51401234#msg51401234