Arif, the icon suggests these files are showing as PDFs not SolidWorks files- you will have to change the file associations. Right Click > Open With > Choose Default Program as the SolidWorks Launcher.
Check these posts andd see if the solution offered in these helps or not:
In Windows, when you select a file, and then select it again (not double click), it defaults to thinking you want to change the name of the file.
If you are having trouble with your double click speed, you should be able to manage it in your mouse settings.