First of all many thanks to everyone who replied to my Marker Beacon problem. I still don't get the bleeps but let's move on to the next problem!

I am flying Wilco's 737-300 and using PM. My aircraft trim is always out of the green zone - around 12.5 degrees nose up. How do I sort this? I'm told it has something to do with the text file. Help please - as you can guess I'm not too clever with all this.