hello how is bitcion stored on usb flash I want to know about it
The Electrum wallet has a portable version that you can download from the official website and unpack to a USB Flash Drive. Keep in mind that, while this allows you to run your wallet on any device, there is a security risk to be aware of:
Since we now have a subforum for Electrum, I am rewriting here what I already said in other threads. I hope it's more visible in its own thread.
It is not safe to use a portable version of Electrum on an insecure computer!
Do not download Electrum from another source than electrum.org, and learn to verify GPG signatures.
https://electrum.org/#download