I need to change a Data Frame's Unit Display which is currently Degrees Decimal Minutes.. I open View | Data Frame and then in the dialog under Units Display, select Decimal Degrees from the drop-down menu.and click Apply. Nothing happens. When I click on OK to go back to the Data Frame the Unit's Display is unchanged, still showing Degrees Decimal Minutes. How to fix this please? Thanks very much.
Dan, thanks. There are two coordinate systems associated with this data frame:
The data frame's base map is ArcGIS topographic. On top of that is a georeferenced 1918 USGS topo map which is associated with the NAD coordinate system. I'm assuming that the GCS coordinate system is associated with the basemap, but maybe not? Maybe that's the problem?
When I went to do that this popped up:
Pressing the Transformations ... button showed this:
I have no idea what these additional GCSs are associated with. Having never encountered this before, not sure what the right thing to do is.
Could also be a glitch. Choose the Display Unit as "Decimal Degrees" (Data Frame Properties) > Save the document. Close all ArcMap sessions and opening it again.
If it doesn't work out, try opening a new MXD and define the desired coordinate system to its data frame > Change the Display Units. Then add the respective layers to it.
I know this thread is ancient but there is an ESRI bug report that addresses the issue that I found while observing the same problem today. https://support.esri.com/en/technical-article/000011883
The bug is appropriately titled:
Bug: After setting the data frame display units to Degrees Minutes Seconds, the display units cannot switch to Decimal Degrees