Yesterday anounced news about finding vulnerability in Ledger wallet.
How to store bitcoins safe ?
I am tell in this topic how to do this.

- First of all you need to create wallet (bitcoin core or other) and encrypt him with unique password, wich not coincides on any other internet services.
- Then print paper with this password or private key and laminate them (this is for extra last chance backup). Store your piece of paper offline
- Then buy usb flash drive and create on them txt file and put in them your password. Flash drive allways store not connected to the your computer, only when you need to do payment connect it and open your text document and copy past password. Why only copy past, because if your pc infected by malware or keylogger it cant steal password.
- After doing transaction fastly disconnect flash drive.

Double Spending
If your wallet was hacked and your coins sent to another wallet but still not confirmed you can back your funds.
You must create new transaction with very high fee and sent coins to other your wallet or your friend wallet, if your second transaction will confirmed faster then first you back your funds. Transactions with higher fee have advantage in mempool
P.S. Low transaction speed have benefit when you have been hacked