My tip draw in the graph

I am guessing you are referring to “Statistical info chart”?
It is currently not yet possible to select a point (coming soon). Until then I suggest you simply draw a very small area about your point of interest.
E.g. you put “42.66708012475693, 13.927219098107344” in the search window. When EO Browser moves you to the appropriate location, zoom in to scale level 15 (300m on the scale bar) using +/- tool, so that center remains the same. And then draw an area.

For anyone looking for this, starting from a few months ago EO Browser makes the process easier. User can place a POI (Point of Interest) on the map and get the Feature Info chart in its vicinity.