Wesley
Pitch-shifting or any audio time change can only go by so much before it becomes distorted or doesn’t work.
For example many European films converted for US audiences are 4% faster than originally made. Most people can’t tell the difference but dialog is faster.
The more you increase or decrease the speed after a certain point, even pitch-shifters don’t work.
However instead of using a video editing program, try Audition, Pro Tools, etc as they have better ones built in.
If you want to spend the money, Izotope RX is great.