The Silent Uploads
The Apple ecosystem is built heavily on iCloud integration. When you take a photo on your iPhone, or save an image to the Photos app on your Mac, macOS naturally wants to upload it to iCloud Photos. This ensures your entire library is synced and accessible across all your Apple devices. While incredibly convenient, this automatic background syncing can be problematic if you are on a metered internet connection, if you have limited iCloud storage space (the free 5GB tier fills up rapidly), or if you simply want to keep certain high-resolution image edits strictly local to your Mac’s hard drive.
Disabling iCloud Photos Sync
To stop macOS from automatically uploading your local images to the cloud, you need to decouple the desktop Photos application from your Apple ID’s iCloud storage.
Launch the Photos application on your Mac. In the top menu bar, click on the word Photos (next to the Apple logo) and select Settings (or Preferences on older macOS versions). In the Settings window, click on the iCloud tab at the top. You will see a primary checkbox labeled iCloud Photos. If this box is checked, your Mac is actively uploading your full-resolution photos and videos to Apple’s servers. Click this checkbox to uncheck it. A warning prompt may appear asking what you want to do with the photos currently on your Mac; usually, you will choose to “Download” them to ensure a local copy is safe, or “Remove from Mac” if you only want them in the cloud. Once unchecked, the automatic syncing bridge is broken, and your Mac’s Photos library will remain entirely local.