Well, the confusion you have is merely one of terminology .... Plane's do not have high and low rates, it is the radios that have them....

The Servo's are mechanically connected to the control surfaces. The servos have a limited amount of travel, call that 100% travel. 100% travel will move the control surface an amount that is dictated by the way you have connected the control rods to the servo horn and control horn. The instructions for your plane should indicate what control surface deflection you should have as a "recomended starting point". The right thing to do is to set your control surfaces so that 100% servo travel will give the exact control surface deflaction that the manual recommends. Now, manuals often give High and Low rate deflections. Use the high rate deflections for your settings.

To set and test your control surfaces, you must have your radio switched to "high rates", so figure out which switch to switch, and set it to high rates.

So, at this point, you should have your radio set to high rates, and the control surfaces mechanically set to the throws described in the plane's manual.

Then, in your radio's menus, you can set the low rates. The low rates are usually set as a percentage of the high rates i.e. low rate ailerons will be 60% of high rate. What this means is that 100% stick movement will cause a 60% servo movement. You will have to try different settings for you to get them to match the plane's instructions.

So, at this point, you have set your plane to match the high rates by mechanically setting the control rods for your servos. The Low rates are a % of the high rates. Flipping the dual rate switch togles between the high and low rates.

The purpose of low rates is to make sure that you do not surprise yourself with the agility of the plane and end up disoriented and with a pile of sticks.

As an out of practice veteran, flying a trainer, I would suggest to you that you ignore high-low rates for the moment, and just use high rates. Then just use gentle, and fine-controlled stick movements to control your plane.

If the plane still feels sluggish on the controls, then increase the high-rate throws of the surfaces.

The important thing is that you know what you are setting/changing. If you are on high rates, you can do everything that you could do on low rates, and more. There is no real danger on a trainer of using high rates at the wrong time. In higher performance planes, using high rates at high speeds or other manouvers may exceed the capbilities of the plane...

So, switch to high rates, and stay there.

A more valuable feature of computer radios is exponential. What this means is that the the relationship between stick position and control surface position is non-linear.... i.e. if you push the elevater stick 50% forward, the elevator doesnt't go 50% down. I have my radio set so that almost 75% the control surface movement is in the extreme 50% of the stick movement. Or, in other words, if I push the elevator stick half way forward, the elevator only moves about a third of it's throw. If I push the stick the whole way forward, the elevator moves to it's limit... This means that the controls movements are gentle when you have gentle movements on the stick, and are agressive when you use agressive movements. It is sort of hard to describe in words, but easy to see the results.

gus