Labels are arranged in "levels". The project or root label has a level of 0, the first children have a level of 1. The next set of children have a level of 2 and so on.
In the colours and style dialog, changes can be applied to:
o Just a selected label,
oAll the labels in the same level as the selected label
oAll the labels in the mind map.
Once you set a colour or style for a tab, that colour and style is used for any new labels.