Tan2x,
Try this:
Move your cursor to the bottom right of the window. You will see the cursor change appearance. Hold down the left mouse button and drag the window to the size you want. If you want the window to open this size (everytime) you open it hold down the Ctrl key then click the X at the upper right to close the window.
Regards,
Rick P.

oh, i already performed those actions, and it seems it only retains its customized size only in few days. but anyways, thanks for the help!