The first and third issues have been successfully resolved. I'm currently investigating why the second issue, which is about the inability to save the folder format, is occurring. However, it appears to be unrelated to the other issues. Therefore, if necessary, I will open a new topic to avoid any interference. 
Let me briefly review the causes of the first and third issues.
- DO was running with administrator privileges, which caused problems when exchanging data with other programs.
- On my computer, when I right-click on dopus.exe and check its properties, I can see that "Run as administrator" is checked. (Although I don't know why it was checked.)
- The UAC on my computer has always been set to the lowest level, which means that if a program requires administrator privileges, it will be granted directly without any prompts.
In summary, when I tested the bug yesterday, whether I restarted the computer or completely exited the DO background and then opened it again, DO would request administrator privileges again and agian, which were automatically approved by UAC.
Unbeknownst to me, DO kept running with administrator privileges, which led to the persistent issues and consequently caused the label to fail to turn green correctly and the star rating to not be displayed.
(Additionally, the phenomenon I mentioned at the end becomes understandable. It can be inferred that for a short period after the computer was turned on, DO hadn't had time to request administrator privileges yet, so it could run normally and turn green properly.)