Are all apps and settings being saved to my iTunes backup? I’m currently using the backup to the computer option though I’m not sure where settings for this are. I want to make sure that if I need to replace my phone I can easily just mirror everything to a new one.
Thanks.
Most of your app data and settings and things like wall paper etc are still stored in an iTunes back up - you can also back up passwords etc. if you choose to make an "ecrypted back up in iTunes" - in iTunes 12.9 you can enable this by clicking on your iPhone / iPad in iTunes and selecting "This Computer" and enable "Encrypt iPhone backup" you will need to remember your "encryption password" for future access. Enabling Encryption also backs up health and home data.
iTunes versions after 12.6 versions of iTunes (as mentioned above by NoBoMac) cannot be used to manage apps and screens etc and also no longer store the ringtones or access books. if using iTunes 12.7 and above you will need to manage screens, wallpaper and ringtones on the iPhone and within the iOS. That said, you can still back up the phone with iTunes.
As per NoBoMac's post and link - you can download a special legacy version of iTunes 12.6.5.3 from the link above - but it will not install and is not supported on Mojave (so far - perhaps this will change after the offical release of Mojave)
What version of iTunes are you using? It will help provide more accurate answers.