Keep Two Macs in Sync With iCloud

A desktop at the desk and a laptop everywhere else is the best two-computer setup there is — provided you never have to think about which machine has the file. iCloud gets you most of the way there. Here's the exact configuration, and an honest list of what it won't sync.

The foundation: one account, iCloud Drive on both

1. On each Mac, open System Settings and confirm the same Apple Account at the top of the sidebar. Same account is non-negotiable — iCloud never syncs across two different accounts.
2. On each Mac: your name → iCloud → turn on iCloud Drive (on Sequoia, under Saved to iCloud).
3. Anything you put in iCloud Drive now appears on both Macs within seconds to minutes. Make it your default working area for documents.

Sync the Desktop and Documents too

In the iCloud Drive panel on each Mac, enable Desktop & Documents Folders. Now a file dropped on one desktop appears on the other — the single biggest quality-of-life win of the whole setup. One first-run quirk: the second Mac's existing files land in a subfolder named after that machine (e.g. Desktop – Mac mini) rather than merging automatically; drag them out once and you're unified. Keep an eye on your iCloud quota, since both machines' desktops now live in it.

Turn on the app-level sync

Files are half the story; the daily-use apps sync through their own switches, all under System Settings → your name → iCloud on both machines:

• Notes, Reminders, Contacts, Calendars — instant parity for the small stuff.
• Photos — one library on both Macs; pair with Optimize Mac Storage on the smaller disk.
• Messages — in Messages → Settings → iMessage, tick Enable Messages in iCloud on both so conversations match.
• Safari — tabs, bookmarks, history, and reading list follow you; iCloud Tabs shows the other Mac's open tabs.
• Passwords/Keychain — logins created on one Mac autofill on the other.

Beyond iCloud proper, Continuity adds the finishing touches automatically once both machines share the account: Universal Clipboard (copy on one, paste on the other), Handoff for in-progress documents, and AirDrop for the occasional big one-off transfer.

What iCloud won't sync — plan around it

• Applications. Install apps on each Mac separately (the App Store remembers your purchases; licensed apps usually allow two seats).
• App and system settings. Dock layout, keyboard shortcuts, app preferences — none of it syncs. Configure each Mac once, or use a tool that applies your preferred settings quickly.
• Anything outside iCloud's folders. ~/Downloads, custom folders in your home directory, external drives — invisible to iCloud. Either work inside iCloud Drive or accept those areas are per-machine.
• Huge fast-changing files. VMs and video scratch files sync slowly and churn quota; keep them local per machine.

The workable mental model: iCloud syncs your data, not your machine. Keep working files in iCloud Drive, let the apps sync themselves, and treat everything else as local to each Mac.