mgm help please

Could someone tell me if its normal to have my mgm 160 go to full trottle as soon as you pull the trigger?? i tried to set everything i can think of. its my first mgm so im not sure if this is normal. if i want to go slow i have to play with the trigger becouse as soon as i leave it at the same place vroom full speed i go. theres only full speed or brake. i set the ms to almost 2 sec to so i dont take off tooo fast thanks: