How to lock the Dock on a family Mac

Nobody here is an adversary

Every other version of this problem is about a machine strangers use. A family Mac is the opposite: the people changing your Dock live with you, they are not doing it on purpose, and you cannot exactly revoke their access.

Which changes what a good answer looks like. You are not trying to win. You are trying to make Tuesday look like Monday.

• The size. The divider between apps and folders is a drag handle in the busiest part of the screen, and a child's aim is not precise. One brush and every icon changes. macOS has no undo for it.
• The contents. An icon dragged off the Dock vanishes in a puff of smoke, which is delightful once and a problem forever after. The app is still installed. Nobody can find it.
• Hide and show. Flipped by accident, and now the Dock is gone and somebody thinks the Mac is broken.
• The position. Dragged to the side, which changes the width of every window on the screen.

What Screen Time does, and what it leaves alone

Screen Time and Family Sharing are Apple's parental controls, and they are good at what they cover: which apps can run, for how long, what content is allowed, and when the Mac goes quiet at night.

None of that touches the Dock. There is no Screen Time setting for the Dock's size, position, contents or auto-hide. The two solve different problems and work fine together, but one is not a substitute for the other.

The four keys, and the part people miss

defaults write com.apple.dock size-immutable -bool true
defaults write com.apple.dock position-immutable -bool true
defaults write com.apple.dock contents-immutable -bool true
defaults write com.apple.dock autohide-immutable -bool true
killall Dock

Each one grays out the matching control in System Settings, so it cannot be changed from the interface at all. They survive a restart, a sleep and a macOS update.

They are stored per account. That is the part people miss at home. If the family has separate logins, running these in yours does nothing in anybody else's, and each account needs its own pass. If everyone shares one login, once is enough.

To release one, remove the key rather than setting it to false:

defaults delete com.apple.dock contents-immutable; killall Dock

Every key with its type is in every Mac Dock defaults command.

Separate accounts are worth it anyway

If the Mac currently has one login that everybody uses, giving each person their own is the larger fix, and the Dock is only part of what it settles: separate Desktops, separate Downloads, separate browser history, separate everything. The Dock then stops being a shared surface at all, and each person's stays as they left it.

The cost is that you configure the locks more than once. That is a smaller cost than it sounds, and it is a one-off.

Pick the removable kind

There are two ways to hold these settings and at home only one of them is right.

• Ordinary locks undo in a click and never ask for a password. On a family Mac this is almost always what you want, because the person who needs to change something later is you, in a hurry, on a Sunday.
• A configuration profile holds through Terminal, through a restart, and through deleting whatever set it. It is removed on purpose in System Settings, General, Device Management. Reach for it only if somebody in the house has found the Terminal commands and enjoys using them.

If you want the middle ground, Still Dock can require Touch ID to turn a lock off, so it is not something anyone passing the keyboard can casually undo, and it is still one fingerprint away for you.

Recent apps, which changes on its own

macOS adds a section of recently used applications to the right of the Dock. On a shared login it fills with whatever the last person opened, and it changes every day whether or not anyone touched anything.

defaults write com.apple.dock show-recents -bool false
killall Dock

The four locks do not remove it. It is a separate setting, covered in how to stop recent apps appearing in the Dock.

A sensible setup at home

1. Arrange the Dock the way it should be, and take off anything nobody uses.
2. Turn off recent apps.
3. Apply the locks. Size and contents are the two that matter most with children; position and auto-hide are the ones that cause the "the Mac is broken" phone call.
4. If there are separate accounts, do it in each one.
5. Leave them removable. You are the person who will need to change this.

Common questions

Will this stop my child installing apps?

No. It stops the Dock changing. Restricting what can be installed or opened is Screen Time's job, and the two are fine together.

Do I have to do it in every account?

Yes, if the family has separate logins, because these are per-account preferences. A profile pushed by an MDM can cover a whole device at once, but an MDM in a house is a heavier tool than the problem deserves.

Can my child undo it?

With the ordinary locks, yes, if they find the Terminal commands. With a profile, not from Terminal, though it can still be removed on purpose in System Settings. Neither is a safe, and neither is meant to be.

Will a macOS update clear the locks?

No. They live in the account's preferences rather than in the system, so an update leaves them alone. They also survive Migration Assistant to a new Mac.

What about the guest account?

Anything set in one login does not appear in another, so set the locks in the accounts your family actually uses. If an account is one macOS clears between sessions, the settings go with it.

Is this different from a school or shared Mac?

The commands are identical, the situation is not. See a classroom Mac, a library or public Mac, or the shared Mac guide for the general case.