About editing animation

After you create a frame or a keyframe, you can move it elsewhere in the active layer or to another layer, remove it, and make other changes. Only keyframes are editable. You can view tweened frames, but you can't edit them directly. To edit tweened frames, you change one of the defining keyframes or insert a new keyframe between the beginning and ending keyframes. You can drag items from the Library panel onto the Stage to add the items to the current keyframe.

To display and edit more than one frame at a time, you use onion skinning. See Onion skinning.

To insert frames in the Timeline, do one of the following:

To insert a new frame, select Insert > Timeline > Frame.
To create a new keyframe, select Insert > Timeline > Keyframe, or right-click (Windows) or Control-click (Macintosh) the frame where you want to place a keyframe, and select Insert Keyframe from the context menu.
To create a new blank keyframe, select Insert > Timeline > Blank Keyframe, or right-click (Windows) or Control-click (Macintosh) the frame where you want to place the keyframe, and select Insert Blank Keyframe from the context menu.

To delete or modify a frame or keyframe, do one of the following:

To delete a frame, keyframe, or frame sequence, select the frame, keyframe, or sequence and right-click (Windows) or Control-click (Macintosh) the frame, keyframe, or sequence and select Remove Frames from the context menu. Surrounding frames remain unchanged.
To move a keyframe or frame sequence and its contents, select the keyframe or sequence, then drag to the desired location.
To extend the duration of a keyframe, Alt-drag (Windows) or Option-drag (Macintosh) the keyframe to the final frame of the new sequence.
To copy a keyframe or frame sequence by dragging, select the keyframe or sequence, then Alt-drag (Windows) or Option-drag (Macintosh) to the new location.
To copy and paste a frame or frame sequence, select the frame or sequence and select Edit > Timeline > Copy Frames. Select a frame or sequence that you want to replace, and select Edit > Timeline > Paste Frames.
To convert a keyframe to a frame, select the keyframe and select Modify > Timeline > Clear Keyframe, or right-click (Windows) or Control-click (Macintosh) the keyframe and select Clear Keyframe from the context menu. The cleared keyframe and all frames up to the subsequent keyframe are replaced with the contents of the frame preceding the cleared keyframe.
To change the length of a tweened sequence, drag the beginning or ending keyframe left or right. To change the length of a frame-by-frame sequence, see Creating frame-by-frame animations.
To add a library item to the current keyframe, drag the item from the Library panel onto the Stage.
To reverse an animation sequence, select the appropriate frames in one or more layers and select Modify > Timeline > Reverse Frames. There must be keyframes at the beginning and end of the sequence.