Here is how you increase/decrease the speed of your video clip
Step 1: Select the video you want to adjust the speed off by clicking it.
Step 2: Click the Clip option on the action bar to open up the Properties Panel on the left.
Step 3: Click on the Speed tab, and now you can now adjust your clip's speed by sliding the speed cursor to the right/left.
Q) How do I speed up only a certain part of the video?
A. You can speed up certain parts of your video by cutting/splitting clips at portions of the video you want to speed up and then adjusting the individual clip's playback speed.
Q) Can I make my video play in slow motion?
A. Yes, you can. To play your video in slow motion, select the video clip and adjust the playback speed from the left panel by dragging the speed slider to the left, the slowest being 0.1x.