Changing your Gmail password on your iPhone is a crucial step in maintaining your email security. Here's a simple guide to help you through the process:

1. Open the Gmail app on your iPhone.
2. Tap on the menu icon at the top left corner (three horizontal lines).
3. Scroll down and tap on 'Settings'.
4. Select your email account.
5. Tap 'Manage your Google account'.
6. Go to the 'Security' tab.
7. Under 'Signing in to Google', tap on 'Password'.
8. You might need to sign in again for security purposes.
9. Enter your current password, then create and confirm your new password.
10. Tap 'Change Password'.

Remember to use a strong, unique password to better protect your Gmail account from unauthorized access.