So here is an example, I'm using 0.8mm cold rolled steel. Starting on the right I went too fast and you see the weld is proud and almost shiny. Then I slowed down and let the puddle form and you can see the change in the weld, goes flatter and the filter rod flows into the parent metal.
There was no change to the settings, no change in gas, I just slowed down a little. Flipping it over, again right to left with the metal butted hard up against each other I didn't get penetration because I was too fast. but then looking right to left you can see I get good penetration once I slowed down.
Hope that made sense and it helps