To speed up or slow down a section of your recorded video you first seek to where you want to start your speed change then click the "Tools" menu button above the timeline and select "Speed" then the "Speed Up" or "Slow Down" option or you can just press the "S" key and then the "U" or "D" key start the tool. One thing to note before starting is that using the speed tool will remove any narration on the section we change so its best to use the tool before you add or replace narration on the recording. Select the section to speed up or down by dragging the purple bar along the timeline. You can also click around the timeline then use the "S" key to jump the start to that point or the "E" key to jump the end to your current seek point. Select how much faster or slower to run the video by clicking the arrows here. If you want to Preview what the speed change will look like then you can press the Preview button which will seek right before the change and start playing then apply the speed change over the section and stop shortly after it. Once you're ready to commit you press the OK button or the Enter key. Anytime you add an edit to a recording it is automatically saved on your computer. After the speed change is added a colored span will show on the timeline showing where it happened. If you want to change or remove it you can seek back to that spot on the timeline then click this icon which will bring up a menu so you can adjust the change using the arrow keys or remove it by pressing this icon. You can also use the undo or edit history drop down to go back in time before you added the edit if you'd like to remove it. The last used tool will be listed next to the Tools button above the timeline so you can easily use the same tool again by clicking on it here.