It is not possible to change the pass phrase of a deterministic wallet.
Workaround for Difficult Pass Phrase
You can create another wallet and if you are happy with the new pass phrase, back up the new pass phrase (to make sure you don’t lose it) and then:
- sweep the addresses from the old wallet using the new wallet, or
- login to old wallet, send your funds to an address in the new wallet
Transaction fees apply to the both approaches.
Workaround Using Quick Access URL
If the complexity of your pass phrase is the only thing that bothers you, you can create and use a Quick Access URL.
If you want to avoid having to remember the pass phrase, Counterwallet lets you create a Quick Access URL. In existing Counterwallet you can find that feature in Settings, while for new wallets the option is presented upon creation and also available in Settings.
Your Quick Access URL must not be shared with users who you do not want to have access to your accounts.