The recommended way to use Koala Wallet is to create your own Recovery Phrase, adding inside it accounts of any coins you need to use. However it's also possible to import individual private keys, restoring access to accounts not linked to any of the Recovery Phrases set up in your Koala Wallet app.
Viewing imported accounts
On Koala Wallet's main screen, tap the active wallet name at the top left corner, then select "Imported Accounts"
Importing more accounts
While viewing the imported accounts on Koala Wallet's main screen, tap the "+" button to add new accounts as usual.
If you already have any imported accounts, you will see the available tokens to be added to those accounts, otherwise the list will be empty. To import a different account, press the import button at the top right corner of the screen.
Here you can choose which coin you want to be imported. Paste or scan the QR code of the private key you want to import. Finally set a name so you can easily identify the account. Press the "import" button to confirm.
The new account will be added to your Koala Wallet's main screen. If done correctly, this account will have the same address and balance as any other wallet app where you use it in. If you want to access tokens inside that account, press the "+" button again and the available tokens will be immediately listed.
Security and backup
Private keys should always be kept private. Anyone who has access to an account's private key has full control over it and can steal all funds in it. Individual private keys are not backed up by your Main Wallet's Recovery Phrase. It's essential that individually imported keys are also individually backed up. You can read more about it here.
You can review imported keys by tapping the active Wallet name at the top left corner and selecting "Manage wallets"; or by going to Koala's "Settings - Manage". Tap an imported account and select "backup" to show its private key.