Just in case you want to reset to factory defaults:
1. Press the up and enter button
2. switch on the iron
3. you will see an A flashing, press up to navigate to U and press enter, select 0 + enter.
All done, now you will have to configure it back to your settings.
Not in the manual, got an email from Hakko.
I have to agree with most of the folks, the user interface of the FX888D simply sucks. But once you get used to it, you don't usually play around the temperature settings that much. I've configured the presets to the configurations I use and that works out great.