How to display from the Wallet itself
1. Click on the Extension icon in Chrome to display Wallet, and click on the "Account icon" in the upper left corner of Wallet
2. When the account list screen appears, click on "...".
3. Click "Edit Account...".
4. Click on the "eye icon" of the private key
5. You can check your private key.
How to add it from the settings screen
1. Click on the Extension icon in Chrome to display Wallet, and then click on the "gear icon" in the upper right corner of Wallet
2. Go to the settings screen and click "Account" under "Wallet
3. From the list of accounts on the right, click the "..." button to the right of the account name you want to view the private key for.
4. Click the "Display Private Key" button on the sub menu
5. Your private key will be displayed.