Hi ,
The Location settings in Twinmotion 2023.1 can be found in Ambience > Location.
There is a known issue currently causing that problem where any media you create will show an incorrect location preventing you from adjusting the geolocation of the image. A fix is currently being tested and is expected to release in our next update. In the meantime, the workaround for this is to set the geolocation outside media mode, then to create a media, which should inherit the location.
The team is currently looking into an option that will allow you to copy and paste settings between media, which would allow you to set the same location settings for multiple media simultaneously. You can upvote this feature on our roadmap here: Copy / Paste Settings Between Images - Twinmotion Public Roadmap
Regarding the option to add a light theme, I recommend submitting this as an idea on the roadmap here so the team can look into adding this.
Best,
Raghib