If it goes up to "E" max, I bet you need to kick the speed up to arout 5-6ish. If it only goes up to "d" I bet you need to be in the 6ish range. Just totally ballparking here but 2 is definitely WAY WAY WAY too slow on your wire speed. If the big plate was equally as thick and you're just running a 110V welder you probably could've kicked it up to the next letter too.
For instance, my lincoln goes up to E... When I'm welding in my C setting I'm around 5.5, when I'm in D I'm running about 6.5. It varies a bit depending how much wire is on the spool but that's roughly where I'm running at. Mine is 220V though also so my C and D settings are probably much hotter then yours.
I think I've only welded on my "E" setting once ever and it was like 3/8" thick plate I was working with. I did most of the race truck on either "D" or a combo of A and B for the sheet metal stuff and depending what I was doing.
You could always kick it up to the highest letter, put it at like 7ish and just lay down a stack of tack welds on top of each other. Will look pro and do fine for anything not life concerning. It's the cheater way to weld but it works! You didn't hear that from me though! LOL
Oh and in comes Merrick with the closer!!!