Use the term defocus for more search answers. There are unique things you can accomplish by manipulating the focus, but just leaving it alone will work under regular usage.
I have two color acrylic that I use for earrings and other projects that I want to stand out without painting and I have excellent settings for it. If you manually select a focus of 0.060 then the ‘saved’ settings will show
As can be seen, some colors resist the laser and adjustments to the parameters were required, but are immediately on hand once the focus is manually set.
I experimented with this a bit and found another interesting use. Making a fast score look like a time consuming engrave is possible, as described below.
Note that if you do this only for a segment of the project the laser stalls for several seconds while it is changing parameters, then proceeds. This is apparently normal (although it can cause a moment of panic if not expecting it).