1. Tap the menu button
2. Tap Bookmarks and then use the sort icon to:

• Sort by the newest bookmark
• Sort by the oldest bookmark
• Sort your bookmarks from A to Z
• Sort your bookmarks from Z to A

#Tap the menu button

1. Tap Bookmarks and then use the sort icon to:

• Sort by the newest bookmark
• Sort by the oldest bookmark
• Sort your bookmarks from A to Z
• Sort your bookmarks from Z to A

There is another entry "sort as user defined", but how can I define that?

@wxie, this option isn't specifically to allow a custom order to be defined on Android devices, but rather to allow Android to display the specific custom order of synced bookmarks the user already specified on Desktop.

So after reordering bookmarks on Desktop, then syncing, it should match this order on Android.