If that's the case:
create a chart (bar/table, whatever u want);
as dimension :
Negozio and put a limit :
as a measure: sum( Vendite)
this will show only the top 3.
Now, if u want to have control on the top n u wnt to show; please download this extension:
(unzip it and put it under, documents/qlik/sense/extensions..
and create a variable vTop; give it value 3
and in the extension; call the vTop variable :
and in ur dimension; instead of fixating the number to 3 like in the first screenshot; call $(vTop)
with that, each tme u enter a new number; top yourNumber will be shown