Which one is the safest way to store bitcoins? I often hear that becomes thefts. I guess some of them are not heard even.
The two safest options are either a paper wallet or an offline wallet. My bitcoins are currently stored on an old offline android phone which I wiped and installed Bither on, it's easy to transfer funds on and of to and you can only access the coins by having physical access and the password so it's pretty secure.