MSCONFIG ram help needed

Hi

I have windows 7 64bit,
Well I found out that ACT OF WAR cannot be played with windows7 that is over 2 GB of ram. On here I have 6Gigs
So I found a solution to this problem by going to my system config,Boot,
Advanced options. There I had brought my maximum memory from 6144 which
was what it came with to 2000 which it is at now. And I applied it, an
restarted my comp, and wonderfully my game worked.

Now that I am no longer playing the game I wanted to
bring the maximum memory back up to 6144 again. But every time I do change it through the ms config option, it just goes back to 2000 after saving and re-starting the computer. I have tried it 5 times, I select the maximum memory 6144 and save and restart but it kepps on reverting back to 2000 ?So my question is/ Is this a problem? and how can I bring it back up to
the original 6144 or 6 gigs of ram ? memory(if i can)

Thank you