If you turn off daylight saving, the system clock will no longer be set forward or back at the start or finish of daylight saving, and you may have to set the clock manually.
As always we start from the default screen which will be similar to one of the images below.

Press the info key (key 7). You are now in the main menu, and the screen will be the same as the image below.

Press the down arrow key (key 6) six times. As before you may press the up or down arrow keys to scroll through all the menu items. The screen will be now be the same as the image below.

Press the right arrow key (key 5). In the event that daylight saving was off, the screen will be the same as the image below. If you are turning daylight saving off, then "Now:" will be "On", and "Set:" will be "Off".

Pressing the up arrow key (key 4), will toggle the "Set:" parameter. i.e. If like the image above it is reading "On", pressing the up arrow key will set it to "Off". When you have the desired setting press the enter key (key 8), and the setting will be accepted, and you will be returned to the main menu.
If you have changed your mind, pressing the left arrow key (key 3), will return you to the main menu without changing the circulation setting.

You can now press the left arrow key again to return to the default screen, or press the up, or down arrow keys to select a different menu item.