The most consequential four syllables in Western Christianity are an addition to this text. Where the creed says that the Holy Spirit proceeds from the Father, Latin usage came to say from the Father and the Son, Filioque. The addition appears in Spain, spreads through the Frankish churches, is sung in Charlemagne's chapel while Rome still resists it, and is accepted at Rome in the eleventh century.
Two arguments are tangled here and they are worth separating, because they are often fought as one. The first is canonical: may any local church alter a creed issued by an ecumenical council, whatever the merits of the alteration. The Eastern answer has been consistently no, and on this ground even Orthodox theologians who find the doctrine defensible reject the procedure. The second is theological: is the doctrine itself true, and does it compromise the Father as the sole source within the Trinity. Here the Eastern tradition is divided in emphasis but broadly negative.
The dispute is a standing marker of the division between the Orthodox and Western churches, and it was one of the grievances aired in 1054 and again at every attempt at reunion since. Modern practice has softened in places: some Western liturgies omit the word when the creed is sung with Orthodox Christians present, and joint statements have distinguished the doctrine from the wording. Neither church has changed its position on who may amend an ecumenical creed.