Have an older IPOD Touch -- downloaded newest IOS - downloaded upgrade to I Tunes. now have issues

If your iPod is now on iOS 6.1.6, that suggests that either it had a very old version of iOS on it, or that it has not been recently updated. But to move on:

• Connect your iPod to your iTunes Library and click on the iPod icon when it appears:

• That will display the Device/Settings/Summary pane. Your screen will look similar to the one shown below:

• On that screen, is the box named Manually manage songs and videos ticked (checked)?
• Now click on Device/Settings/Music (1.) - (just below the Summary option). You should see a screen similar to the one shown below:

• Is the box named Sync Music (2.) ticked (checked) or not?
• If the Sync Music box is ticked, which option shown at 3 is selected? (You may, or may not, see the boxes numbered 4)

Before anything else, I think we need to establish exactly which versions of iOS and iTunes that you have, because "latest version of iOS" is open to interpretation and even "newest version of iTunes" may not be as simple as it seems.

If your iPod is a 4th generation model, that suggests that you have iOS 6.1.6 installed on it. It is not capable of running later versions of iOS.

The latest version of iTunes is (on the day of writing this post) is 12.12.2.2. But if you downloaded iTunes from the Microsoft Store (rather than directly from Apple), updates are automatic but hidden to the point where you are not actually aware of which version you have.

So, to move forward:

• which version of iOS do you have on your iPod? (Look in Settings/About)
• if you click on iTunes' Help/About iTunes, does it tell you which version you have installed?

• turning to the music:
  • are the songs in your iTunes Library, and do they play in the Library?
  • finally (for now), where are you obtaining the new music (that won't go onto your iPod) from? Are they purchases from the iTunes Store or a known retailer such as Amazon, or are they mp3s from YouTube?

Do you have iCloud turned on?