Q: iTunes, buttons do not work

Hello Ton Van Hest,

From what I gather, some buttons and links aren't working when you click them in iTunes on your iMac. You may be able to isolate and resolve the issue by launching iTunes while holding the Command + Option keys on the keyboard, as described below.

iTunes 12 for Mac: Keyboard shortcuts

                 

Open iTunes in “safe mode” (without external plug-ins)

Option-Command (while opening iTunes)

If the buttons and links respond normally when launching iTunes in Safe Mode then you should try moving any plug-ins located in the folders quoted below.

iTunes: May become unresponsive when connecting iPhone, iPad, or iPod touch - Apple Support

• Mac OS X: 
   
  • ~/Library/iTunes/iTunes Plug-ins (The "~" represents your Home folder)
   
  • /Library/iTunes/iTunes Plug-ins
• If any files are in this folder, move them to the Desktop temporarily.
• Open iTunes and test to see if the issue is resolved. If so, you may leave these iTunes plug-ins removed. If you wish to re-use these iTunes plug-ins, consult the vendor for the iTunes plug-ins to see if any updates are available.

Also, if the issue only occurs when your iOS device is connected to your Mac, try running through the complete article that's linked above.

Ciao.