Here is a picture that should be similar to what you are looking at. It is the channel detail for a channel/track (click the "e" icon on the mixer channel). The following things are critical and numbered on the pic:
1. This button activates the EQ band. If it is not lit up (green on my version), your EQ is not on.
2. This sets the frequency for the EQ. The inner knob (and the number box above the knob) is for the amount of cut or boost. You don't need to worry about this for a high pass/low cut, but for a shelf or notch, it is important.
3. This knob is for the "Q" or width of the EQ. The far left EQ can be set up as a High Pass (with the knob all the way to the right) as it is in this example, or a shelf EQ (with the knob all the way to the left) where you simply attenuate the frequencies by a certain number of dB. Anywhere in between, it will act like a normal parametric EQ band.
4. This is the EQ bypass switch. If it is yellow, the EQ's are bypassed and won't affect your signal. If it is green (as in the pic), the EQ is active.