When you use a spinner to animate a parameter, a few right-click options help manage the animation.
+right-click the spinner arrows to remove an animation key on the current frame. -
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+right-click the spinner arrows to remove all animation on this parameter. - When animating with Set Key, create an animation key by changing a spinner value and then +right-clicking the spinner arrows.
(When you animate with Auto Key, simply changing the spinners value sets a key.)
Important: To do these actions, you must right-click the spinner arrows, not the numeric field. Right-clicking the numeric field opens the Spinner Right-Click menu instead.