Every device is different, some are manual knobs, some are touch buttons.

You can generally understand it, but if you really don't understand it, you can ask the waiter. It's not a shame. What else do you want the service staff to do?

But I tell you seriously, most people can understand it, it's really not that complicated …, and there are a few cases where there will be temperature control and you need to set it yourself, but that kind is rare, but it does exist. Personally, I think it's ok to be within180-220. The rest depends on your skill. Don't burn it, just be golden yellow.