Volume keys not clicking when adjusting except when I hole the shift key

Good Morning,
I hope this post finds you well.
I'm not sure what I've done but I was trying to work out the keyboard command for turning my screen curtain on and off. and I've somehow switched off a setting.
You know how when you press volume up and down it clicks by default, mine only does that when I hold down the shift key now.
I tried shutting my Mac down and restarting again but no, still the same.
Does anyone have any ideas?It's a Macbook Air 2020 running an M1 chip.
If you could let me know, that would be brilliant.
Thanks in advance.