I am Australian, (Most unfortunately), and yet my grammar is in order - in fact I have met more Englishmen illiterate in the language than any other!

About your gaming difficulty however, it is a technologically natural law in your case, you cannot change the difficulty in the midst of a campaign.
This is because of so many factors and variables that rely of difficulty settings, and the rather colossal bother of redirecting them to suit your acknowledgement of mistakes.

Now - when you start a new campaign be aware of this;
That on a very hard campaign setting, you are likely to find that the game is rather like Resident Evil 3, where you are the last survivor with a healthy brain - and the entire world is out to kill you.

Hard is generally rather fitting, as factions behave like ambitious young nations.

Medium makes everyone alot more sedate, factions plan more slowly, and create defensive lines often in my campaigns on medium - so this is my usual choice.

As for battles, unless you want the AI to have a huge advantage and to lose all realism in unit settings - choose medium!

It is quite acceptable, no one is going to call you names or question your honour or decoration if you are more comfortable with a lower setting.