Hi, David,
That's an odd glitch. Applying Control-i and Control-o shouldn't affect the speed of the clip.
You can correct the speed by doing by selecting the clip and doing a Modify/Reset Speed. Or, you can do Edit/Undo until you get back to where you were. Or, you can select the clip, then click on the speed adjustment icon (the one that looks like a little clock face) in the tool bar at the top right of your screen. In the speed adjustment box that appears, click on Normal to get back to where you were.
Hard to know what happened here without a step-by-step of your work flow. I am just speculating here, but possibly you activated the speed adjustment handles (Select clip, then Control-click, and select Show Speed Editor in the drop down menu. When you do that a little gray dot will display in the upper right hand corner of the clip, that is a speed adjustment handle. When you put your cursor on the dot and drag left to shorten the clip, the speed will increase. Dragging right will lengthen the clip and slow it down. In the course of editing you might have moved the activated speed adjustment handle when you tried to trim the clip.
In the event that it is an actual glitch in the program, you can try deleting preferences by opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if the problem persists.
If the problem still persists, try placing your media into a newly created project and see if that solves it.
-- Rich
