How to reproduce: 1) Write one word without any formatting 2) Write another word and format it as underlined (or bold/italic/strike-out) 3) Now select both words with mouse or keyboard => Both words will be formatted equally afterwards. This makes knotes almost impossible to use as a todo list for example. As a side note, the behavior does not seem to apply to all other formatting options like font sizes, colors, sub/superscript...
If I understand the report correctly, you are not using knotes ...
Well, I was indeed referring to knotes (the thing in the system tray), but I just checked, it applies to the plasma notes widget (Desktop sticky notes) as well.
Hello! This bug report was filed for KDE Plasma 4, which reached end-of-support status in August 2015. KDE Plasma 5's desktop shell has been almost completely rewritten for better performance and usability, so it is likely that this bug is already resolved in Plasma 5. Accordingly, we hope you understand why we must close this bug report. If the issue described here is still present in KDE Plasma 5.12 or later, please feel free to open a new ticket in the "plasmashell" product after reading https://community.kde.org/Get_Involved/Bug_Reporting If you would like to get involved in KDE's bug triaging effort so that future mass bug closes like this are less likely, please read https://community.kde.org/Get_Involved#Bug_Triaging Thanks for your understanding! Nate Graham