SUMMARY There are two colour controls in Kate: 1/ View>Colour Scheme and 2/ Settings>Configure Kate>Colour Scheme Setting both of these to, in my case Monokai changes the current display to the desired colours, however if Kate is closed it opens with another colour selection. STEPS TO REPRODUCE 1. change the 2 colour options (1 & 2 above) to my desired choice. 2. exit Kate and restart 3. OBSERVED RESULT The new session of Kate always defaults to a default purple colour. EXPECTED RESULT That the input colour selection be displayed. SOFTWARE/OS VERSIONS Operating System: Kubuntu 21.04 KDE Plasma Version: 5.22.5 KDE Frameworks Version: 5.86.0 Qt Version: 5.15.2 Kernel Version: 5.11.0-37-generic (64-bit) Graphics Platform: X11 Processors: 16 × AMD Ryzen 7 5800X 8-Core Processor Memory: 15.5 GiB of RAM Graphics Processor: NVIDIA GeForce GTX 1080/PCIe/SSE2 ADDITIONAL INFORMATION
You are likely not setting the right option. Open Settings -> Configure Kate -> Color Theme Change the "Default theme for kate" to the desired option. This option is located at the bottom of the dialog. I know it is confusing that we have two options and it often happens to me that I expect the top option to change the theme but it doesn't change. Also, you don't need to change the "View" theme unless you want it to be something different from your default.
Indeed it is confusing but your advice is correct.