Okay when I do this it tells me Unable to access jarfile and java virtual machine launcher says this, it tells me this when I try to run minecraft with this entered, I found out where it's located and I type cmd in the run bar thing but tells me the unable to access jarfile.
Ok first I go to the control panel and then open java, next I go to the java tab and click view, then there is a row and I type in the runtime parameters section -Xmx2048M and once I do that I click ok then I click apply.
I've seen some posts on this before and piediepie I don't really think we can trust you on that considering you only have 2 posts not saying your not right but it's just harder to believe.