The Delta Marker Properties dialog box is opened when you double click on a delta marker or right-click on a delta marker and select "Properties" from the pop-up menu which appears. The three checkboxes below control what information is displayed in the delta marker label. You can select all three, but at least one must be selected.
Display Delta Identifier: Selecting this checkbox adds the delta identifier (∆) to the delta marker label.
Custom Label: Selecting this checkbox allows you to add your own text to the delta marker label. Enter the desired text in the Label text entry box to the right.
Default Label: Selecting this checkbox adds the x and y value of the delta marker to the delta marker label. The data that will be displayed appears to the right of the checkbox. Note that if the delta marker is between a line marker and a data marker, only one value will appear.