PDFs randomly open in Preview instead of Acrobat

Question

Not a major but a semi-annoying problem is that totally out of the blue all PDFs will start opening in Preview instead of Acrobat. All PDF file icons change from the PDF icon to Preview, as if the default program switches. Then it goes back by itself, for no apparent reason after I manually drag PDFs into Acrobat. Just happens randomly and I wonder why that is and how to prevent it, because it happens often enough to be a minor nuisance.

Answer 1

Right click then select get info. open drop down that says "Open With" then change app.