at the top of the screen in the various menus, you should see
settings -
these can be changed for both video & audio; just adjust the way
you prefer.
As for slowing down, I guess you could
(1) change the speed of the video
or
(2) insert some blank spaces - or duplicate images - within your
video.
BTW - I'm assuming you're dealing with your own videos,
because tampering with another's work would be considered
plagiarism.
BTW 2 - I certainly hope someone else, with more knowledge, of this
will respond to you anon;
the reason I keep my replies cc'd to the list.