Q: On iTunes, there is a box next to the song title. This is used to determine whether a song is synched or not to an iPod. Is there a way to highlight select a group of songs and check or uncheck en masse instead of one song at a time?
A: You can easily check or uncheck ALL of the displayed items by holding down the CTRL key (Windows) or CMD key (Mac) while clicking on any one of the checkboxes. The checkboxes of ALL of the displayed items will be simultaneously checked or unchecked.
Note that this affects all of the displayed items, and not merely those items that you have highlighted in iTunes. If you want to restrict your selection, you can either use the iTunes Browser to choose a specific Genre, Album or Artist, or filter based on a Search criteria or a playlist.
One other point worth noting: The checkboxes are not used only to determine whether a song is synced to your iPod, but will also affect whether or not a song is played in iTunes. Unchecked tracks will never be played by iTunes unless you specifically select them, so if you have any tracks in a playlist that are unchecked, these tracks will also be skipped when playing back your music from this playlist.
If this is a concern for you, then you may want to consider managing the music on your iPod based on selected playlists, rather than based on checkboxes.