I see. I think there is no need to set the default reader. If you want to use another soft for opening a PDF file just click with the right mouse button on icon of a file of the PDF type and then choose the "Open With" option. There should be listed all programs you may use for opening of the file. It is enough to click the one you want. If there aren't you can choose "Choose the Default Program" option. In the new window you will find all programs for accessing the file. The basic programs are see directly in the window but the entire rest of them may be hidden at the "Other Programs" menu and accessed by clicking of the hat mark on right side. If you chose the proper program and there is marked a small square at line with "Always use the chosen program for the opening of the file type", by clicking OK button you will set the chosen program as the default one for the type of files. If your program isn't listed there you may use the "Browse" button , (at the same line), for finding the program on your HDD. Usually all installed programs are saved with the path.. C/Program Files/folder with the execute file. That's all. If you aren't satisfied with the new program you may set back the Adobe Reader in the same way. Oh.. by the way... if you set another program for a file opening, the Windows will change the basic icon for all files of the same type. As a result, the PDF icon of the Adobe Reader seen so far, will be changed to the Evince one for instance.