This could be slightly different depending on the operating system version.
What program is used to open attachments depends on the type of the attachment (file extension).
One way to change the default program is:
– In windows explorer, right-click a file (any file) of the type you want to open with some other program different than Wordpad, and click on “Open with” (you may need to press shift while right-clicking the file in order to get the “open with” option to appear.
– click on “choose program”
– mark to select the check box “always use the selected program to open this kind of file”
– select the program you want to use to open that type of file from the programs list.
– Click on “Ok”.