Apple Macintosh LC - Manual (Page 125)

5. Release the mouse button when the outline of the icon you're
repositioning is where you want it.
The icon appears at or near where you dragged its outline, with one side
bordering the closest other icon.
If necessary, repeat steps 3 through 5 to adjust the relative positions of
other monitors.
6. Choose Restart from the Special menu to implement the new monitor
positions.
You don't have to close the Control Panel before choosing the Restart
command.
The monitor positions you set remain in effect until you change them.
After you have set the monitor positions, the pointer moves from one screen
to another across the borders where the monitors' icons touch in the Control
Panel.
Designating a main monitor
If you have more than one monitor, one will be designated the main monitor,
where the Finder's menu bar will always be displayed. You can change the
designated main monitor.
Monitors of different sizes: It's a good idea to make your larger monitor
the main monitor. If the smaller one is the main monitor, some programs will
restrict the window size to the size of the smaller monitor.
1. To designate a main monitor, first choose Control Panel from the Apple
menu.
The Control Panel opens with the General section displayed.
2. Scroll if necessary to locate the Monitors icon, then click it to display
the Monitors section.
The Monitors section of the Control Panel appears.
3. If necessary, check the numbers of your monitors by placing the pointer
on the Identify button at the lower-right corner and holding down the mouse
button.
Skip this step if you don't need to verify the monitors' numbers.
A large number appears in the center of each monitor's screen while the mouse
button is held down; that number corresponds to the number of the icon in the
Control Panel.
4. Drag the white menu bar from the top of one monitor icon to the icon of
the monitor you want to be your main one.
An outline of the menu bar moves with the crosshair pointer as you drag.
5. Release the mouse button when the menu bar's outline is where you want
it.