If there is a new game version available, then your device may automatically install it (if you have auto updates enabled) or you can update manually.

On iOS/Apple devices:
• Open the App Store app
• Search for Idle Bank Tycoon
• Tap and drag down at the top of the screen to refresh the page
• If an update is available, it will show an "Update" button you can tap

On Android devices:
• Open the Google Play Store app
• Tap your profile icon at the top right of the screen
• Tap "Manage apps & device" and then "Manage"
• Tap the app you want to update. Tip: apps with an update available are labeled "Update available"
• Tap "Update"