Maximizing it will not save the settings.. If someone tells you that, they have no idea what they're talking about.
To save the window size, leave it as normal when it opens, then move the cursor to one corner of the window. The cursor will change from a single arrow to a diagonal double-ended arrow. Click and hold the left mouse button. While doing so, drag the window to resize it to the size you want. Once done, close the window and reopen it as normal. Your size setting will be retained. If not, your registry will need a tweak.