I don't understand the controls at all

[E-Pona]

How do I assign spells to my hotbar?

I press left CTRL, I press dominate human, the R key changes to Dominate human. How do I change back to using my bolt spell? Can I not put bolt on 1,2,3,4,5,etc?

How do I do this at all?

[Mavor]

CTRL brings up the vampire powers wheel - which usually puts you in a form or stance. To leave a form/stance - just hold CTRL again, and click, or hold mouse, on the center of the wheel (the empty space) - your spells will be back in their hotkey slots once you are out of your form/stance.

You assign spells via your Spellbook - you have two spell slots and one ultimate.

[Akulvo]

Press CTRL to select a vampire power, sometimes changing your current abilities like domination form.
Press CTRL again while your form is changed to go back to your default form. Only form change this doesn't work with is Bat Form, which requires you to land using Space Bar.

Also 1, 2, 3, 4, etc are for your weapons and consumables.
Q / E are for weapon abilities
R / C are spell abilities
Space is your dash ability
and T is your ultimate ability

The reason its defaulted this way (you can freely change it as you want in the keybinds) is because the game is designed with weapon swapping on the fly and with a very limited selection of spells available at use during a fight. So even if you do put your spells onto 1, 2, 3, 4, etc, you'll only be able to fill up 1-3 (or 4 if you wanna put your dash on a number key spot but that sounds crazy). Its not like other games where you can get a large variety of spells to put on the hotbar to cycle through rotations and such