Okay,
Even though I gave you basic settings to start at, you never posted pictures or gave a full description of what you were trying to do, or what joint type you were trying to weld in. You say corner joint: inside? outside? T type? etc. Joint prep? Single pass?
Lets break your essential beef down:

You want exact settings that can tell you where something should operate:
Lets consider the variables involved:

1) Tungsten size, type and Manufacturer. Manufacturers of tungstens though supposedly uniform in make are anything but that. I have found great difference in brands and even in packages of the same manufacturer

2) You have infinite settings between the controls. There is a UNLIMITED possible number of settings that will work.

3) Skill level. No matter what setting is given, if the skill isn't there it won't work period.

4) Stickout. How far does you tungsten stick into the join?

5) Arc Length, related to stickout, normally kept as close as possible. This controls you arc cone diameter and the "spread" of heat.

6) Torch manipulation. If the torch isn't worked between the two pieces of metal, and evenly spreading the heat between the two pieces, knitting the puddle together, it'll take more heat to get the job done.

7) Amount of oxidation. Heavy oxidation requires more input to break up the oxidation and a bigger electrode.

8) Gas flow rate. How much gas is flowing? This affects the heating up of the tungsten to a point and the oxidation removal.

9) Gas type...A major factor when welding TIG. A little helium can increase penetration and weldability of some aluminum. Argon is still fine, but a small percent of helium less than 20-25 percent can make a difference.

10) Tungsten point shape to begin with.

There are other factors, but in my mind, this is what usually affects what settings are used the most. I am sure I missed some. It is hard to give hard and fast settings based off the unlimited possible conditions you face. I am not there and cannot possibly give you anything but the broadest guidelines. Experience and one on one training is the only thing that can help get you where you need to be. Tungsten melting can result in wrong AC balance for sure, but if your polarity is set wrong as your plasma torch was, it won't work right when you adjust your AC balance. Long arcs can also overheat the tungsten by spiking up the voltage.(this goes back to corner stickout)

I don't want you to thick I knee jerked my response to you. I thought it out carefully. The point is, people are fooled into thinking there is a magic setting that can make them a good welder or make something work better for them. When, in fact, skill and technique are the #1 and #2 determining factors.