I can't find a way to turn off preview for folders in Dolphin without turning off thumbnails for images and videos.
I find previews of images and videos useful and extremely important, especially for video editing. However, I find the previews shown on folders very messy and distracting, they don't really give me much useful information.
Is there a setting somewhere which allows me to do this?

The other tweak which I would like to make but I can't find a solution for, is to turn off the 'tree' lines when viewing expanded folders in compact or detail view. Is there a way to do this?

sammuirhead wrote:I can't find a way to turn off preview for folders in Dolphin without turning off thumbnails for images and videos.
I find previews of images and videos useful and extremely important, especially for video editing. However, I find the previews shown on folders very messy and distracting, they don't really give me much useful information.
Is there a setting somewhere which allows me to do this?

General->Previews in Dolphin's settings.
You can enable/disable previews for several types of "files" (including folders) there independently.

The "Previews" button is just a general on/off switch.

The other tweak which I would like to make but I can't find a solution for, is to turn off the 'tree' lines when viewing expanded folders in compact or detail view. Is there a way to do this?

What dolphin version and what widget style are you using?

For oxygen you're able to do that in systemsettings or systemsettings5 (depending on the version). Go into "Application Appearance" (or "Application Style")->"Widget Style", and click on the "Configure" button for your configured style, there should be an option "Draw tree branch lines" on the Views tab. Or run oxygen-settings(5) to get there.
There doesn't seem to be such an option for Breeze though.

Btw, AFAICS compact view doesn't even have that feature...

Thank you! I'm a new user of KDE (other than certain individual applications) and I'm finding the configuration options rather overwhelming, but it seems I can set almost everything how I want it - it's just a matter of finding the right settings!