Are you talking about the "Exporting" option on Acrobat's ""File" Menu?
If so, then this creates a file of the PDF in a selected format and you would have to open the program for viewing the type of file that was created.
If not, can you tell us what program you are trying to "Export" form?
Most applications that export or create PDFs have an option for "Settings". Within this feature there should be an option to open Acrobat upon creation. This assumes your program is compatible with Acrobat DC. If it is not, please check for an update to your application.
If you're referring to the PDFMaker plugin it's the "View Adobe PDF result" check-box under the Settings tab.
I’m exporting out of InDesign 2017 and I can’t seem to find the “open upon exporting” either in InDesign or Acrobat Pro DC.
Got it to work – thanks for your suggestions!