Did the Sabbath change to Sunday?

In over 105 languages Saturday translates to Sabbath. In Italy it is called Sabbato, in Russia Subbota, in Portugal Sabbado, in Spain Sabado and in Poland Sobota. All of these names mean “Sabbath” or “rest day” in the various languages.
The fourth commandment of the Bible says Exo 20:8-11 “Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: But the seventh day is the sabbath of the LORD thy God…”
So if Saturday, or more accurately Sunset Friday to Sunset Saturday, is the true Sabbath of the Lord, then why do people go to church on Sunday?
Who changed the day to Sunday, and when? Did Jesus? Do we keep Sunday in honour of his resurrection?
It has been established by many historians and theologians that the books of Matthew and Luke were written between 60 and 80 AD. Luke does not tell us of a day change, but instead he states in Luke 23:56, “…And they rested on the Sabbath according to the commandment.”
Jesus also showed that the Sabbath would still be kept after the cross when He was talking to the Disciples about the forthcoming destruction of the temple in about 70 AD. Jesus says in Matthew 24:20, “And pray that your flight may not be in winter or on the Sabbath.”
Historians also confirm that the seventh day Sabbath was kept by Jews and Gentiles alike, until about 120 AD when the persecution of the Jews for Sabbath keeping became so great that many Christians decided to start keeping Sunday, so as to distance themselves from the Jews. Some began using the excuse that it was in honour of the resurrection, as there was no biblical basis for the change.

In 321 A.D. Constantine, who was a pagan, became Caesar in Rome and when he began to see the balance of power shift from paganism to the Church he passed the first law enforcing Sunday worship in 321 AD. Two years later he joined the Roman Catholic Church and began mingling paganism and Christianity. It was well after 400 AD before Sunday eventually took on the name of the Lord’s Day.
In many papers and documents the Roman Catholic Church openly take credit for moving the sanctity of the Seventh day Sabbath to Sunday, by their own authority, which they say is above that of the scriptures.
“The authority of the church could therefore not be bound to the authority of the Scriptures, because the Church had changed...the Sabbath into Sunday, not by command of Christ, but by its own authority.” Canon and Tradition, p. 263.
So it seems that if we keep the Sabbath on the seventh day, we are following God’s commandment, but if we keep Sunday, we are following the traditions of man. Does that really matter?
The Bible says in Mark 7:6-9 “Jesus answered them, “How right Isaiah was when he prophesied about you! You are hypocrites, just as he wrote: ‘These people, says God, honor me with their words, but their heart is really far away from me. It is no use for them to worship me, because they teach human rules as though they were my laws!’ “You put aside God's command and obey human teachings.” And Jesus continued, “You have a clever way of rejecting God's law in order to uphold your own teaching.”
All Bible references are from the King James Version.