"No one will serve you if you're unpleasant."
Translation:Personne ne vous servira si vous êtes désagréable.
In a previous example (something about not tasting anything if I am in the kitchen) the future - serai - was used. Why is it now to be present tense? I conjugated the thing using tu (picturing this was a friend admonishing another friend) so may that was why it wasn't accepted and not my use of "seras"?
I just did the exact same exercise earlier Jennifer, the two clauses were linked by “quand” not “si”, so “when” not “if”. In the discussion, Jojo pointed out that the subordinate clause had to agree in tense with the main clause ( for “quand” “des que” etc.) but with the exception of the two clauses being linked with “si” as is the case here, where the main is future and the subordinate is present. There may be other exceptions but this is the one that registered.
You're right: https://www.lawlessfrench.com/grammar/si-clauses-conditionals/ This is a conditional sentence of the first type, so it takes présent, with and without the negation.