nice you got most of it right
the reason why it disappears is because growth is low and has a low chance of spawning another circle, my friend was saying the oldest circles should despawn first.
right arrow is for addon buttons up arrow shows addons and right arrow shows (if any addons are enabled) buttons
growth is to increase the amount of circles which is yellow arrow
but each new circle spawn also removes growth so later on it will go back to normal
yellow arrow for increase growth, the arrow pointing right switches to addon buttons, and arrow pointing up raises or lowers the hud which shows the addons.