Top Category to show my side categories in a drop down menu

Hello to all you talented people ! I'm new to opencart and I would love to know if it is possible to have my side menu (10 Categories) showing in a drop down on the top menu bar ... I added them to a parent category but this then removed them from the side I would love for this to work because at the moment if viewing on a mobile my side menu doesn't show.
Many thanks for your time

I'm using Opencart 2.3.02

Yes must mark the categories as show in top nav and that will show them up to 2 or 3 levels. If you want more levels you can get an extension to do that.

Hey there ... if I check the top box it puts them all up there but as separate, so I have 15 or more across the top and non at the side .... I want to keep the side ones but also duplicate so all the side ones are as a drop down too