Method One:
 
Directly through the program, you can use one of the following methods to set the Thenfoxin reader to the default reader:
 
When the first time you open the Fu Xin Reader, the program will pop up a dialog box to ask whether it is set as the default reader, select Yes.
 
Open the Fu Xin Reader and select the Help menu. From the Help menu, select Set as default PDF reader;
 
Open the Fu Xin Reader, select "File" > "Preferences" > "file association" > Check the default setting option under Set as default PDF reader, and click OK.
   
Under Windows XP system, open My Computer > select Tools menu > Folder Options > File type > Find PDF > Click the "Modify" button and select the Fu Xin Reader.
 
Vista and Windows 7 systems, open the Control Panel > Program > Default program > Set the default program, where it is set as the default PDF reader.