Am I missing something?

For my home directory I typically have the folders (Desktop, Documents, Downloads) shown as icons and for (say) documents in the Documents folder I use the 'details' view mode. Since updating to kde applications 19.04 if I change the view settings for the contents of any folder, it changes every folder in my home directory.

I am using Opensuse Tumbleweed, But have also tried KDE Neon and this has the same behaviour since updating to 19.04?

Please check the setting in Configure Dolphin -> General -> Behavior -> View. It sounds like that is set to Use Common properties... where you are expecting it to Remember properties... (I don't know if the default changed recently)

airdrik - perfect, thanks very much.

The default setting must have changed in 19.04 from 'remember properties for each folder' to 'use common properties for all folders'.