Whenever you issue an extrinsic with the Polkadot-JS UI or the Polkadot extension for e.g. the purpose of staking or transferring funds out of your account, you will be asked for your password. 

This is the password you set up when you first created your account. The same one that works with your JSON back up file. 

If your password does not work, check the following details:

  • Is CAPSLOCK on? This is one of the most common issues. 
  • Did you make a typo? Type your password in text file or blank email to see what you are typing. This can also help if your keyboard is switched to a different language.
  • Is there a blank space before or after your password? This can accidentally happen when you copy/paste a password. 

If you have forgotten your password and you really cannot access your account, then you can reset your password by restoring your account from your mnemonic seed phrase. (You can also restore an account with your JSON file, but since that would require the same password, this won't be of use to you.) 

During the process of restoring your account from your seed phrase, you will have the chance to set a new password. For detailed instructions on how to restore an account on Polkadot-JS UI and the Polkadot extension, please see this tutorial