Check System Preferences > Users & Groups > Login Items. You may have specified it to open at login.

EDIT: Also, look at iTunes Preferences > Devices and see if the box at the bottom (Prevent iPods....) is unchecked.

Last edited by jchuzi; 07/27/16 04:13 PM.
Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365