The Qur’an confirms the previous Scriptures (the OT and the NT). but at the same time they deny that they are not changed from their originals. They believe the originals of the Bible (both OT and NT) have corrupted in the copies and that the apostle Paul and apostle John’s writings are teachings that are not the original “gospel according to Jesus”. Muslims some things are true in the OT and NT, but that only the Qur’an can discern what is true and what is false. They read the Bible anachronistically and put Qur’anic filters on their minds when they read parts of the Bible today.
The Qur’an does confirm the Bible in Surah 5:47 and 10:94 and 2:136 and 29:46 and 5:68.
“no one can change the words of God”
وَلَا مُبَدِّلَ لِكَلِمَاتِ اللَّهِ
“And there is no changing the words of Allah” (This phrase is from Surah 6:34, and see 6:115 (116); 10:64 (65); and 18:27
Since we have many older manuscripts than 600 AD, and the Qur’an confirms the Bible at the time of Muhammad, then the Qur’an never says the text of the Injeel (Gospel) or Torah (law or OT) or Zabur of Davood (Psalms of David) was changed.