So you don’t want them to all be at trust level 0, but at trust level 1.
What might have confused you a bit is that higher trust levels are also part of the lower trust levels. For example, when a member becomes TL1 they do not lose being TL0.
You can best see this by looking at your Edit Groups TL 2 - 3 - 4 which indicates there is five TL4s (including the “system” and “discobot” accounts) and one TL3, all of them are also TL1 and TL0
The Users per Trust Level row shows the number of members that have reached the levels.