In the settings window there are two spaces one bellow the add to shelf and another under the sync actions. So if you click the space where the sync actions is or should be it opens sync actions dialog, if you click where the add to shelf is it opens the add to shelf. I was thinking of this.
Of course if it's hard to do it's not that important
. I used the bulk edit to choose to which column to sync and after that I only have to edit what I want to sync to the column - way faster. You can select the similar shelves, edit all and when edit them a little one at a time