The BIP39 passphrase option is disabled when creating a new wallet. This is on purpose because it is a dangerous feature for new users. It's not your normal "send" password, and it's only required when restoring. The extra BIP39 phrase is NOT shown anywhere in-app, and if one forgets it the wallet cannot be restored with just the normal Recovery Passphrase.

It's not possible to add a BIP39 passphrase to your current wallets. What you actually do is create a brand new wallet with a BIP39 passphrase and transfer your coins to it. Here's how to do it:

  1. Back up your recovery passphrase.
  2. Click on "Settings - Manage wallets"
  3. Click on the blue '+' button and then "Restore a Wallet" and enter your recovery passphrase, but this time click on the "advanced settings" and check the BIP39 box and enter any phrase or word you like. Make it memorable. Your funds will be irrecoverable if you forget the phrase. You may wish to write it down and keep it safe, somewhere separate from your recovery phrase.
  4. On the next screen, enter a strong password for transactions.
  5. Add the wallets you will to use.

    Steps 6 to 11 are optional, but you are strongly advised to try restoring again with your new recovery passphrase and your extra BIP39 phrase and check that you are familiar with restoring wallets that have have a BIP39 passphrase

  6. Go to a couple of your wallets, swipe to the Receive tab, and note down/screenshot the receive address given by Coinomi.
  7. Click on "Settings - Manage wallets - Restore wallet"
  8. Enter your recovery phrase click on "advanced settings" and check the extra BIP39 box, and enter the BIP39 phrase or word you entered in step 3.
  9. On the next screen, enter a strong password for transactions.
  10. Add the same wallets as in step 5.
  11. Go to the wallets you examined in step 6, swipe to the Receive tab, and compare the addresses with the ones you noted down/screenshot in that step (6). If they match, you are good to go.

    Then it is a matter of transferring your coins to the new phrase.

  12. In the wallet with the BIP39 passphrase open the "receive" page of a coin you have.
  13. Open the wallet which is configured without the BIP39 passphrase, open the wallet of that same coin, and send to the new address (Copied in step 12)
  14. Repeat steps 12 and 13, one coin at a time until all your funds are on the new addresses.

    If you have a single device, you can use the method described here, where you first note all addresses of the new phrase, recover with the old phrase to transfer the coins, then restore the new phrase again.

You should now have all your funds in your new, BIP39 protected wallets.

Remember that for one recovery phrase you can have many "hidden" wallets, each one of them using a different BIP39 passphrase. You can have a single backup for your recovery phrase, and different BIP39 passphrases generating different and independent wallets. Since those are completely new wallets, on step 3 you may wish to generate a brand new recovery phrase as well. Be sure to have a proper backup of all phrases.

The BIP39 passphrase is standard and it is supported on various Bitcoin wallets, but not all. Due to the way it is implemented there is a chance that it would not work if your BIP39 passphrase has composite letters, for example é, å, ώ (they can be interpreted as a single letter or a plain letter + a letter mark). If you want to be 100% sure that you are not affected from this and be cross compatible, make sure you check that you get the same addresses using the recovery phrase tool (it works even offline, just save the page). If you enter a BIP39 passphrase in the tool and you get the same addresses as in your Coinomi account, then you are OK and you will always get the same addresses as long as you enter that exact passphrase.

Final warning, be sure to backup your recovery phrase and BIP39 passphrase somewhere safe, away from your device.