It happens every single time. You double-click a PDF, expecting it to pop open in Adobe Acrobat so you can actually sign the thing, but instead, macOS launches Preview. Or maybe you're a developer and your .js files keep opening in TextEdit when you clearly need them in VS Code. It’s annoying. Honestly, it’s one of those tiny digital frictions that makes using a computer feel like a chore instead of a flow.
You’d think after decades of software evolution, computers would just know what we want. They don't. macOS has its own internal logic for file associations, often prioritizing its own native apps like Music, Photos, and Mail. If you want to change default program to open file mac settings, you have to take the reins yourself. It isn't just about clicking a button; it’s about understanding how the "Launch Services" database in macOS actually handles your data.
The "Get Info" Method: The Only Way to Make It Permanent
Most people try to right-click a file and select "Open With." That works once. It’s a one-night stand for your file. The next time you click that file, macOS goes right back to its old habits. To make a marriage stick between a file type and an app, you have to use the "Get Info" inspector.
First, find a file that’s giving you trouble. Let’s say it’s a .webp image that keeps opening in Safari when you want it in Photoshop. Right-click that specific file and hit Get Info, or just highlight it and tap Command + I on your keyboard. A tall, skinny window pops up. Look halfway down for a section labeled Open with:.
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If that section is collapsed, click the little grey arrow to reveal the dropdown menu. Pick your preferred app from the list. But wait—you aren't done yet. If you stop here, you’ve only changed the setting for that one specific file. To apply this to every single file on your Mac with that extension, you must click the Change All... button right below the dropdown. A confirmation dialog will ask if you’re sure. You are. Click continue.
Why Does macOS "Forget" My Preferences?
Ever notice how sometimes you set a default and then, three weeks later, it reverts? This usually happens after a major macOS update or a significant app update. When you install a new version of macOS (like Sequoia or whatever the latest build is in 2026), the system occasionally resets the Launch Services database.
There’s also the "Sandboxing" issue. Apple is obsessed with security. Sometimes, if an app isn't "notarized" properly or if it’s living in your Downloads folder instead of the Applications folder, macOS might treat it with suspicion and refuse to keep it as a default. Always make sure the app you want to use is actually dragged into your /Applications directory. It sounds basic, but you'd be surprised how many people run apps directly from a mounted .dmg disk image and wonder why their settings won't save.
The Right-Click Shortcut (The "Option" Key Trick)
If you don't want to go through the whole "Get Info" rigmarole for a quick change, there is a "hidden" modifier. Right-click a file and look at the "Open With" menu. Now, hold down the Option key.
Watch closely.
"Open With" magically transforms into "Always Open With." This is a faster way to change default program to open file mac without opening extra windows. It’s great for one-off fixes, though I’ve found it slightly less reliable than the Get Info method for system-wide changes.
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Handling the "Developer Cannot Be Verified" Headache
Sometimes you try to change the default to a niche third-party tool—maybe a specialized markdown editor or a retro media player like IINA or VLC—and macOS throws a fit. It’ll say the app "cannot be opened because the developer cannot be verified."
This is Gatekeeper doing its job, albeit aggressively. To bypass this, you usually have to go to System Settings > Privacy & Security and scroll down to find the "Open Anyway" button. Once the app has been cleared once, macOS will usually let you set it as a default without further complaints.
When Files Have No Extension
What about files that don't have a .jpg or .txt at the end? macOS uses something called Uniform Type Identifiers (UTIs). Even if the extension is missing, the system looks at the "header" of the file—the first few bits of data—to guess what it is.
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If you're dealing with a lot of extension-less files (common in Unix-based workflows), your best bet is to use a third-party utility like SwiftDefaultApps. It’s an open-source preference pane that gives you a much more granular view of what app handles what URI scheme or MIME type. It’s a bit "power user," but if the standard "Get Info" method is failing you, this is the nuclear option.
Actionable Steps for a Cleaner Workflow
Don't let your Mac dictate how you work. Take ten minutes today to audit your most-used file types and force them into the apps you actually prefer.
- Audit your PDFs: If you hate Preview, use
Command + Ion any PDF and force-switch everything to Acrobat or PDF Expert. - Fix your Text files: Most people prefer a code editor like Sublime Text or VS Code over TextEdit. Change the
.txt,.json, and.htmlassociations early. - Media Check: If QuickTime struggles with your
.mkvfiles (and it will), set VLC as the "Change All" default for that format. - Reset the Database: If things are truly broken and your icons look like blank white sheets of paper, open Terminal and run:
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user
This forces macOS to rebuild its entire list of file associations from scratch. It takes a minute and might make your fans spin, but it's a miracle worker for corrupted settings.
Once you’ve mapped your extensions properly, the "Open With" clutter disappears. Your Mac starts feeling like a tool you've tuned specifically for your hands. It’s worth the effort.