Fossil makes dozens of watch models, with varying numbers of buttons on the left and right side. Some have digital displays, some have analogue displays and some have both. There isn't one set of instructions for setting Fossil watches that will apply to all Fossil watches. Fortunately, Fossil makes the instruction manuals for their watches available online.
Pull the crown out on the right side of the watch until it clicks once.
Turn the crown clockwise to the correct time.
Pull the crown out further to make it click again and rotate to set the date, if this feature is available on your watch.
Push the crown back in.
Press the upper-left button on the side of the watch to get to the mode that you want to reset, whether it's the time, date or alarm setting.
Press and hold the lower-left button on the side of the watch to make one of the fields flash. Once you do, you've put the watch in set mode.
Press the lower-left button to advance through the different fields to make the field flash that you want to set.
Press the lower-right button on the side of the watch to change the flashing digits.
Press and hold the lower-left button get out of set mode.
If your watch has both analogue and digital displays, use both of the instructions above to set the analogue and digital time separately.