Hi James,
To set summer time, press the bottom right button in until the bottom dial hand is pointing at set, then pull out botpm right button so display flashes, now press bottom left button to switch summer time on, or vice versa to switch off. Now press bottom right button to finish.
Hope this is ok.
Simon
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix wrist watches.