You certainly know what is toolbar (a set of buttons with icons for quick access to functions). To configure it, use a context menu called by a right mouse click on the toolbar:
Flat Tool Bar - select here the appearance of the buttons.
Large Buttons - select here the size of the buttons.
Show Tooltips - if checked, a short description of the button function will appear if you will stay with the mouse cursor on the button.
Customize Tool Bar - invokes a dialog, in which you can add buttons, remove buttons or change button position.
Alignment - set here alignment of the Tool Bar in SPLOT main window.