Help with m4b files

I’ve been able to use mp3tag to update chapter titles for m4b files, and it’s updated in VLC but not iTunes or the audiobook player I use. (BookPlayer on Iphone)

The problem seems to be the player using the Itunes/Quicktime metadata and not the Nero metadata after looking it up.

I’ve looked in FAQs and goggled and there seems to be no way to edit or delete the Itunes/Quicktime metadata? Did i misunderstand and if it’s possible to edit could someone help me with how to do it?

It would also be solved if anyone knows of an audiobook player on Iphone that uses Nero metadata but I haven’t found one.

See e.g. here:

Yes, Mp3tag can't edit QuickTime chapters at the moment — only reading and removing QuickTime chapters is supported. On writing, Mp3tag creates a copy of the existing chapter data as Nero chapters. These chapters are used at further edits, which also implies that the original QuickTime chapters can contain outdated data.

You can try foobar2000 on iOS, it's not a pure audiobook player, but it supports and prioritises Nero chapters and is free. You'd need to add the folder with your audiobooks via Settings → Media Library.