Hi Pablo51, you will need to attach the EA to each chart.
If you leave everything as SetByStrat it will use the default settings that the strategy uses, i.e. TrendSurfer will use the TrendSurfer defaults, however, if you change the setting from SetByStrat, the EA will use that setting instead of the default. Hope that helps. 😁
Sometimes you get the bear; sometimes the bear gets you.