Most file types have a default app that will launch when you try to open that file. For example, double click on a file with a .docx file extension, and Microsoft Word will start right up displaying the file you opened. Occasionally there is the need to open a file in a different app than the default one set on your computer. There may even be times when you’d like to reassign a specific file type to always open in a certain app.
Let’s say that you’ve been given a file with a .txt file extension. This is a text file that will open in TextEdit if double clicked, but Microsoft Word is just as capable of reading this type of file. To have this file open in Word instead, right click on the file itself, and choose OPEN WITH from the drop-down list.
A list of possible programs will appear with the default app at the top and other apps your Mac thinks it could use below. Just choose the app you want from the list, or, if it isn’t in the list, choose OTHER to pick from any app on your computer.
If you wish to change the default app that a single file or any file with that extension open with, right click on the file, then choose GET INFO. This will open a window with information on that file. If the OPEN WITH section is not expanded, click the arrow on the left to expand it.
Click the OPEN WITH drop down to choose an app for opening that file. From now on, double clicking that file will open it in your newly chosen app. If you wish to make this the default app for opening any files with this file’s extension, click CHANGE ALL.
Jason Merrill, Mac & iOS Consultant