Zero Z...Change Bit on double run

Try to make this a good question so people (and me) understand.
Heard touch off z zero in the works. It’s says to raise bit a little before cut begins. Is that a round about guess where material is?
What would you need to do if you had to change bits after first or second (so on) runs. Does it reset back to (x,y,z) zero to begin next run.

@JosephWenclewicz I am sorry I do not understand the question. Is it possible to rephrase it?

In video for easel, you show placing bit at lower left. Then place bit almost touching wood. Usually there is a touch off for the bit. So let’s say first run, u use large bit to remove a lot of material, when you change to a smaller bit, how do you zero out materal? For a more detailed bit. Does it return to 0,0,0 preset start position? Hope that makes more sense. Iike your x-carve. Just trying to justify or save for a ShopBot or Laguna. Need to get my feet wet in cnc wood, and your product looks great for the price. The 12x12 won’t do.

Oh yes. Easel gives you the chance to zero it after you change the bit. It moves up in the Z but moves back to X 0 Y0. Then you touch off the top of the material to set Z 0.

Also check out this thread on saving the home position. Easel is free you can try it right now.