Is it permissible to read the Qur’an from a computer or phone, and does the reward differ from reading it from the Mushaf?

There is no harm in reading the Qur’an from a computer or a phone. Reading while looking at what is being read is better, as it combines reading and looking. There is no difference in reward between reading from a physical Mushaf or from a screen, as looking at the writing is achieved through both.