Start with a favourites list
Open a kids channel and hold the OK button on the remote. Choose add to favourites and repeat that for the channels your children may watch. The list then appears as its own category in the menu.
Close the rest
In the settings of IPTV Smarters and TiviMate you will find parental control. There you choose a PIN and tick the categories that only open with that code.
Agree on a starting point
On the kids' tablet, set the favourites list as the start screen. They always begin at their own channels and never have to scroll through the whole list.
Keep the list up to date
Children quickly grow out of their channels. Go through the favourites list every six months: remove what they no longer watch and add what suits their age. That keeps the list short, and a short list is the easiest for young children to use with the remote.