The max_thumb_size parameter is used to controll the thumbnail size. You must re-upload images after you change that parameter as picture sizing is done on upload. See maxigallery wiki page for available snippet parameters.
"He can have a lollipop any time he wants to. That's what it means to be a programmer."
Thank you doze. But there is another problem: Thumb size is 125px, but next thumb in a row is 200px. So there is a big hole between thumbs. I don’t find a solution get thumbs more closer.
Perhaps you actually want to create square thumbnails? Seen info about this from the sticky topic.
"He can have a lollipop any time he wants to. That's what it means to be a programmer."
Indeed - but what you mean with "this sticky topic"?