Default apps are set on the basis of file type. If you have, for example, a PNG file the same program will open it and all other PNG files on your system. That’s not to say you cannot open it with other apps. You can. You just have to select the app and that takes a few more clicks. On maOS though, you will find that you can set a default app for a single file. It’s honestly a pretty neat feature. Here’s how it works.
Default app for file
Open Finder and navigate to the file that you want to set a specific default app for. Right-click it and select Get Info from the context menu.
In the Get Info window of the file, expand the Open With section. Under it, you will see a dropdown with the default app for opening that particular type of file selected. Open this dropdown and select the app you want to open this particular file with.
That’s all you need to do. DO NOT click the ‘Change all’ button. If you do, it will change the default app for all files of this type. In the screenshot below, you can see the Get Info window for two different PNG files. For one file, the app that will open it is the default Preview app whereas, for the other, Chrome will open it.
The difference is that now you can simply double-click the file and it will open in the app that you’ve set. You won’t have to right-click and go through the Open With option to select the app.
It is important that you remember which file has been set to open with a different app or you might later end up wondering what’s wrong your Mac.
If you need to set the file’s app back to its default one, return to the Get Info window of the file and select the default app from the Open With dropdown.
If the dropdown doesn’t list the app that you want to open the file with, you can click the Other option and pick any app from your Application folder. Alternatively, you can also click the App Store option and it will open the Mac App Store to a selection of apps that may be suitable for viewing the file in question. You may not be able to open the Mac App Store for files that have been downloaded from the internet.