You can use the Window pane of Terminal preferences to change window settings, adjust the background color, set the window size, and then choose the amount of information Terminal retains.
Settings list
To modify a setting, select it from the list, and then select from the options in the Settings preference pane.
To create a new setting, click the Add (+) button.
To delete a setting, select it in the Settings list, and then click the Delete (-) button.
To duplicate a setting, select it in the Settings list, and then choose Action menu > Duplicate Settings.
To restore the standard default settings to their default configurations, choose Action menu > Restore Defaults.
To use a setting created on another computer, choose Action menu > Import, and then select the Terminal settings file from the dialog.
To export a setting, choose Action menu > Export, and then select the location where you want to save the file.
Background
To change the background color of the Terminal window, click Color, and then select a color in the Colors palette.
To make the Terminal window translucent or transparent, adjust the Opacity using the slider.
Window Size
To increase or reduce the width and height of information displayed in a Terminal window, enter the number of columns and rows you want.
Scrollback
To set a limit to the number of rows in the Terminal window that you can scroll back through, click “Limit number of rows to” and enter the new limit.