Welcome to the forum @geoffry_wharton ! I’m glad to hear you’re enjoying Dorico so far.
Tooltips aren’t available for a number of buttons at the moment for technical reasons, but it’s intended they’ll make a triumphant return when possible.
As a new user, albeit one familiar with how notation software work by the sounds of it, you may enjoy some of our resources for new users – including our First Steps guide (a walkthrough written for Dorico 3.5 of creating and formatting a short piano piece) and all kinds of videos on the Dorico YouTube channel, such as this playlist for beginners.