Every desktop operating system has a slider that decides how quickly you have to click twice for it to count as a double-click. People reach for it for two very different reasons: because double-clicking has become hard work, or because the mouse has started double-clicking on its own. It is the right control for the first problem and it cannot touch the second, and the reason why comes down to a gap of about thirty times.
What the setting actually controls
It is a deadline, not a speed. Microsoft's own definition is that the double-click time is the maximum number of milliseconds that may occur between the first and second click. Two clicks inside that window are one double-click. Two clicks outside it are two separate clicks.
On Windows the slider runs from 200 ms to 900 ms and ships at 500 ms. The confusing part is that the Fast end is the smaller number: dragging toward Fast shortens the deadline, so you have to click more quickly to beat it. Dragging toward Slow lengthens it to 900 ms and gives you almost a full second. The value lives in the registry at HKEY_CURRENT_USER\Control Panel\Mouse under DoubleClickSpeed, and the API behind it accepts up to 5000 ms even though the slider will not go there.
Where to change it
On Windows 10 and 11, open Settings, go to Bluetooth & devices, choose Mouse, then Additional mouse settings. That opens the old Mouse Properties dialog, and the Buttons tab holds the Double-click speed slider with a folder icon next to it for testing. The folder opens and closes when a double-click registers, which makes it a reasonable way to feel out a setting before committing to it.
On macOS the control is in System Settings under Accessibility, then Pointer Control, labelled Double-click speed. Apple has moved it between the Mouse pane and Accessibility across releases, so if it is not in one it is in the other. macOS offers no numeric value and no registry equivalent.
Why it cannot fix a mouse that double-clicks by itself
This is the part worth the arithmetic. When a micro-switch wears out, its metal contact stops settling cleanly and oscillates for a few milliseconds, sending two electrical signals where you made one press. Engineers call it contact bounce, and it has been measured carefully. Jack Ganssle activated a range of switches 300 times each and logged the bounce, reporting an average bounce of 1.6 ms and a worst case of 6.2 ms. Broader engineering guidance puts the usual range at 1 ms to 20 ms.
Now put the two numbers side by side. The tightest deadline Windows will let you set is 200 ms. A chattering switch delivers its phantom second click in single-digit milliseconds. Even at the Fast end of the slider, the false click arrives roughly thirty times sooner than the shortest window the operating system offers, so it lands inside the deadline no matter where you drag the control. There is no position on that slider that excludes it.
The setting and the fault are not even measuring the same thing. The slider filters by time between two clicks you made. Chatter is one click that the hardware reported twice, and by the time the operating system sees it, the damage is done in the mouse.
When changing it is exactly the right fix
If double-clicking has become physically difficult, this slider is the correct and underused answer. Hand tremor, arthritis, reduced grip strength, and simply getting older all make two clicks inside 500 ms harder than they used to be. Dragging toward Slow to 700 ms or 900 ms costs nothing and often removes the frustration completely.
The opposite direction has a use too. If files keep opening when you meant to click two things in a row, your deliberate second click is landing inside the deadline. Shortening it toward Fast makes the system treat those as two separate clicks again. Try the folder icon in the Buttons tab after each nudge rather than guessing.
How to tell which problem you have
The question is whether the second click came from your hand. If two windows open when you clicked once, if a drag drops halfway across the screen, or if it only started happening on a mouse a year or two old, that is hardware and the slider will not help. If it happens only when you are clicking two different things quickly, it is the deadline, and the slider is the whole fix.
A measurement settles it faster than a guess. Our Double Click Test logs the gap between clicks in milliseconds. A cluster under about 40 ms is quicker than a person can click on purpose, which points at the switch rather than the setting. If that is what you see, the repair options for a worn switch are the next thing to read, and none of them involve this slider.
One honest limit: neither the slider nor a browser test can tell a worn switch apart from driver software double-firing on its own. That is a separate elimination, and unplugging a mouse utility or testing the mouse on another computer is what does it.