Go into the console in the wallet and type getstakesplitthreshold. You can change that value with setstakesplitthreshold . My understanding is, that would have to be smaller then 8994 to split your output. I'm not sure if or what the default is.
This feature is nice to automagically prevent your blocks from becoming to large.
I executed this command and came out this value:

{
"split stake threshold set to " : 2000
}
Do I need to change something? Thank you in advance.
