When you start your Klever Wallet app, you will be asked to enter a PIN code. This is your password for the app. There is no way to recover your PIN code when you forget it. To change or reset your PIN code, you have to reset your wallet. Note, to be able to restore your wallet you need the secret 12-words SEED. So, always make sure to to have a safe backup of your 12-words SEED.
When you restore your wallet after resetting it, you can set a new PIN code. Note, the old PIN code is not required to perform the wallet restore. Please, take a look at the following article about how to reset your Klever Wallet: How to reset Klever WalletYou also find inside the article a link for a tutorial about how to perform wallet restore.