iTunes doesn't auto start

when I connect my iPhone to my computer iTunes will not start. I have to click the iTunes icon to start the program.

I have taken your advice and regarding the feature being optional and have gone to the iPhone Summary page. but there is no "Open iTunes when this [device] is connected" option and nowhere to place a checkmark in the box next to it.

I have checked for updates and am currently running itunes 12.10.10.

Please can you help.