After these proceedings the Council [i.e. the Synod of Ariminum] was dissolved. All returned in gladness to their own provinces. For the Emperor and all good men had one and the same aim, that the East and West should be knit together by the bond of fellowship. But wickedness does not long lie hid, and the sore that is healed superficially before the bad humor has been worked off breaks out again. Valens and Ursacius and others associated with them in their wickedness, eminent Christian bishops of course, began to wave their palms, and to say they had not denied that He was a creature, but that He was like other creatures. At that moment the term Usia was abolished: the Nicene Faith stood condemned by acclamation. The whole world groaned, and was astonished to find itself Arian. NPNF2: Vol. VI, The Dialogue Against the Luciferians, §19.
It’s simply too difficult to generalize about “everywhere believed” what group x teaches for all time.