My Wallets
Why My Wallets Metamask and other wallets generate new accounts from the same mnemonic phrase (generated after installing the wallet).
If the mnemonic phrase gets exposed, all of the accounts associated with it are exposed.

To get a new mnemonic phrase, without this app, you have to
  1. write down the mnemonic phrase (or all the private keys of each account you have created)
  2. reset the app (deletes all the data)
  3. generate a new mnemonic phrase
  4. import your accounts (MetaMask allows importation by private key only)

WARNING: keep your mnemonic phrase and private keys very secure.