My rule of thumb, "that'' (aquela/aquele/aquilo) to maintan distance, in time or space, "this" (isto/esta/isto) to refer to things close to us. 

    There are expressions in wich you use "that" e.g. that´s right (certo, você está certo, é isto...) and there are the relative pronoun "that".

    If you have any expression or phrase that raises doubt, please bring to EMB and the guys here will give it a stab.

   PP.