How Much Ram Should I Put in My Virtual Machine?

I have 3 Gigs of RAM on my laptop and just installed VMWare Player on it. It automatically set it at 1 RAM as recommended whe I was installing it. I am running my posting scripts on it and they seem a bit sluggish, the cursor a bit jerkish and a few times some problems happened with formatting of posts to CL using my scripts that work just fine on the same machine in main/host profile. I adjusted the timing of some steps (increased by 1-2 seconds each) and it's running just fine now.

However, I cannot for some reason increase RAM using the vertical toggle bar or by typing in to 1.5 Gigs. I turned VM off or tried it while it was active in settings and the toggle bar and the type in window are not allowing any input.

Anyone can help? Thanks!