Your services were listed alphabetically. A haircut you do twenty times a day sat below a treatment you do twice a month, just because that one starts with an A.
What is new
Under Services, the ⋯ menu next to New service has Change order. With it you put the services in each category in the order you want, using the up and down arrows.
You see that order everywhere: in the booking widget, on your site and in your own list of services.
What does not change
Your services stay in the same order as before until you move one yourself. A new service goes to the bottom.
The order applies within a category. The order of the categories themselves is set under Manage categories.