Thanks. this is good to point out as the editing screen has the speed set at the slowest (the turtle) by default.Been waiting for this for a long time. Finally we have it!
If you set the speed to slowest, then you can't change the duration of the slow-mo effect.
If you set it to slow or slower (the first two steps) then you will get 2 handles that allow you to change the duration.
While on the slowest, it will make an extreme slowdown for around 0.5 seconds before the mark, and from there continue at normal speed.
My suggestion is that you leave the video unedited, and edit it on your PC. That is, if you want to make some good videos.
Care to share what you use to edit these slow motion vids on your PC with?