Help Please: Confusion about machine setup (grind, portafilter size, programming)

[vinylcafe]

Hey there experts,
Newbie looking for some guidance.
I have an old commercial grade espresso machine that I am getting dialed in.
Using the 'single' espresso button, I'm using 18g of ground coffee, getting 36g of liquid coffee out in about 25 seconds and I think it tastes pretty good.
Am I setup all wrong? i ask this because, I have a button for a 'long', a 'double espresso', and a 'double long' on my machine. These seem impossible to use without having an entirely different grind size.
My portafilter basket is a double (I think) and is pretty full with 18g in it.
Please advise. Was I supposed to get dialed in using the 'double espresso' button?
Thanks for any insight!

 

[Musicphan]

The buttons are what they call volumetric controls.... they simply dispense X amount of water. You can typically adjust them somehow to dispense the desired amount of water.

 

[cofeesniin00]

Maybe the problem is in button