I figured it out by looking at my .sh or .bat files
first step is to ,odify the JVM memory in the JMeter batch file
In jmeter.sh
JVM_ARGS=-Xms512m -Xmx4096m
in jmeter.bat
set JVM_ARGS=-Xms512m -Xmx4096m
2nd step is to modify HEAP="-Xms512m -Xmx4096m" in the JMeter batch file:
in the jmeter.sh
HEAP="-Xms512m -Xmx4096m"
in the jmeter.bat:
set HEAP=-Xms512m -Xmx4096m