How switch to the testnet?
To switch the testnet version, go to the app settings and continuously tap the Tonkeeper logo for 3-5 seconds.
These actions will launch the 'Dev Menu,' where you need to activate the toggle for 'Dev mode':
Afterward, go to the main page, click the "Add Wallet" button, and select "Testnet Account." Then, enter your seed phrase to authenticate in the wallet.