Allocate more RAM without going into preferances

HI,

Mcreator has told me that there is not enough RAM allocated. It tells me to go into the preferences, gradle and then add more. However, when I start it it is downloading stuff so I cant go into preferences and then when the window pops up telling me what to do, I cant do it then and I cant do it after because the failure window pops up and then Mcreator closes. Is there any other way to do this? If not than can you please allow a minute before the failure window pops up or make preferences pop up after the RAM messgae. 

Thank in advance