Q: my ipod touch will not update ios 6.16

Your 4th generation iPod can not be upgraded further.

If it is the first generation iPod there is no way to update it. Sorry.

The only iPod with iOS 6.1.6 is a 4G iPod.

The original iPod can only go to 3.1.3

It won't work on my apps on my ipod touch

Maybe this will help but you provided very little info about your problem:

Starting when iOS 7 was released, Apple now allows downloading the last compatible version of some apps (iOS 4.2.1 and later only)

Install the latest compatible version of an app on an earlier version of iOS or OS X

Starting when iOS 7 was released, Apple now allows downloading the last compatible version of some apps (iOS 4.2.1 and later only)

Install the latest compatible version of an app on an earlier version of iOS or OS X

https://support.apple.com/en-us/HT201377

App Store: Downloading Older Versions of Apps

https://sites.google.com/site/appleclubfhs/support/advice-and-articles/app-store -downloading-older-versions-of-apps-ios

You first have to download the non-compatible version on your computer. Then when you try to purchase the version on your iPod you will be offered a compatible version if one exists.