Please be more specific.
If I click the Music pane under Devices (iPhone), it only lists all my songs, then the Sync button.
Did you mean to click the Summary tab after selecting my iPhone in iTunes?
It has several options, including Automatically sync when this iPhone is connected, Sync with this iPhone over Wi-Fi, and Sync only checked songs and videos.
I presently have all three checked.
Do I uncheck these, then click "Apply"?
Will this remove all songs from my iPhone?
Then I should re-check these options again and click "Apply"?