Change Default Program
Do you have a Word Document (.doc) that you would like to always open in Pages, or perhaps you would like all Adobe Acrobat Files (.pdf) to open in Preview.
No matter what document(s) you wish to change default programs on, the solution is simple.
Select the document and choose File>Get Info (Command+I). Find the Open with section, and if it’s not expanded, click the arrow to expand it. You can then click the drop-down menu to select the program you would like to always open the file you have selected.
If that is the only file you wish to change to that default program, then you are finished and you can close that window.
However, if you would like to change all file types like the one you selected (for instance, all .pdfs), click Change All… to make that the default program for all files with that extension.