There are a few ways to change your 1Password master password:
1. From the 1Password app, go to Settings > Security and click Change Master Password.
2. If you have a 1Password account, sign in to your account at 1password.com, click your name in the top-right corner, and then click Account Settings. Under Security, click Change Master Password.
3. If you’re using a standalone vault (not syncing with an account), open the vault in 1Password and choose File > Change Master Password.
That’s it! Once you’ve changed your master password, all of your 1Password data will be updated with the new password.