Sorting private channel prefix

I have a multiple private channels.
It’s a logically separate by 2 groups.
Private channels sorting by alphabetical.
I want to use some prefics to sorting some groups by already up in group list.
But it work only for digit and then sorting by second symbol.
Maybe it have some special symbol, that already up in list, but i try many varyable symbol. work only digits, but its no good.