Change Downloads preferences in iTunes on PC
In the iTunes app on your PC, use the Downloads pane in iTunes preferences to choose to download items automatically, and choose the size and quality you want.
To change these preferences, choose Edit > Preferences, then click Downloads.
When you make purchases from the iTunes Store on your iPhone, iPad, iPod touch, or on another computer, the purchased items are automatically downloaded to this computer.
To automatically download Apple Music songs you add on other devices, select Music (Apple Music subscribers only).
Always check for available downloads
iTunes displays the number of items you previously purchased from the iTunes Store but didn’t download.
Download full-size HD videos
Select to download the highest-quality high-definition files available for videos you purchase or rent from the iTunes Store. Higher-quality files use more storage space.
Download high-quality SD videos
Select to download the highest-quality standard-definition files available for videos you purchase or rent from the iTunes Store. Higher-quality files use more storage space.