_katy Said:
"Itunes: Ive been having a hard time backing up my iphone and im a new mac user. I do not have itunes downloaded on my mac but I want to be able to backup my iphone by plugging it into my mac. If I cannot download iTunes on macOS Catalina 10.15.6 then what should I do?"
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No More of iTunes:
There is no longer an iTunes application for macOS (Catalina is what you have installed). The TV app plays Movies and TV Shows, whereas the Music app plays music.
Learn More Here:
What happened to iTunes - Apple Support
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So, to Update your iPhone.
Use a the iPhone itself or a computer (a Mac or a PC even) to Update it. There are two important steps: Backup first then Update.
1. Backup First: Make a backup of your device using iCloud or your computer. That way you can have something to restore you iPhone from, should anything go wrong with the update installation.
2. Then, Update Using Links:
Disable Cellular when updating on the iPhone.