When I download an Assessment from Assessing Projects I also find it does not automatically open in Microsoft Word on a Mac. If you hold down the "ctrl" key while clicking on the downloaded file it brings up a dropdown menu. Drag down to "Open With" and select Microsoft Word. (Note ... you may have to select "other" at the bottom of the list and navigate through your application folder to find Microsoft Word.) When I download an assessment and open it this way, it keeps the formatting found in Assessing Projects. I make sure I do a "save as" and change the document type to Word so it becomes a native Microsoft Word document.
By the way - due to this challenge on Macs, I often recommend Mac users download these Assessments in Microsoft Excel format. The formatting always seems to come through as it was online and it opens up natively with Microsoft Excel on a Mac.
Glen's solution is a good one. I believe that when you do that the first time, you will have a little box you can check to let the software know you would always like to open this type of file with the program you choose.
Even on PC's sometimes a file type gets associated with the incorrect program and you have to go into the folder options to indicate with which program you would like that file type to open.
Computers- not as smart as people! (But frustrating sometimes!)