Very unsecure app besides. Only store small amounts of Bitcoin in WoS.
There are currently no lightning wallets with good security AFAIK.
For a secure, non-lightning light mobile wallet I use Edge wallet. I just move small amounts of Bitcoin from my Edge wallet to WoS as needed.
Edge stores your keys in an encrypted file that is backed up to their servers. It can only be decrypted on your phone using your passphrase.