Unfortunately, Apple now requires all apps submitted to their store to be optimized for iOS7, so we are unable to submit new apps that are optimized for older Apple operating systems. Fortunately, it's not hard to check and see which OS you're running:
- Fire up your iPhone and click the "Settings" icon
- Scroll down and click on the "General" menu item.
- Click on the "Software Update" sub-menu. Right at the top of the page, you'll see which version of the operating system you're running and whether you need to update.