NS

What version of Trados Studio?

It's 2019 SR2.

Sorry, I should have provided more detailed version information. It is Trados Studio 2019 Professional SR2 - 15.2.8.3007.

I have my Project Templates folder in the local drive, but I found another Project Templates folder in an external drive. Even if I delete this folder, it is automatically created when I start Trados again. I wonder if this phenomenon has something to do with the problem...

NS

NS said:

but I found another Project Templates folder in an external drive. Even if I delete this folder, it is automatically created when I start Trados again.

Quite possibly.  If it was me I'd uninstall Studio, disconnect the external drives, reinstall Studio and try again.

Paul, thank you for your suggestion. Reviewing my explanation, I noticed my wording was incorrect. Instead of "external drive," I should have said "My Documents." Sorry for the confusion that might have been caused.

Let me explain again. I have the Project Templates folder in my C: drive and this folder is selected in File > Setup > Project Templates. However, there is another Project Templates folder in My Documents. I deleted this folder again and again, but it is automatically created whenever I start Trados. Is this a normal thing or does it have something to do with Trados Analyse? (Should I still uninstall and reinstall Trados?) I would appreciate your help.

The folder '..\Documents\Studio 20xx\Project Templates' is created when you install Studio and contains the standard templates installed by the system.
You may however have additional own templates and store them wherever you want. 
The menu item  'File > Setup > Project Templates' that you mention only gives you an overview of the project templates that you use and shows in which folder they are located (they can be in different folders). The one important thing in this menu is to set which template you want to be your default template as this is the one that will be automatically used for single file projects. 

Walter, thank you for your explanation about the default template. Now I understand that it is normal that the Project Templates folder is created in My Document even when I have selected a template in the C:drive as my default template.

Maybe I should try uninstalling and re-installing Trados, but I found another suspicious thing... After reading the post in the community (community.rws.com/.../trados-analyse), I checked registries and found "SDLX" under SDL, which appears to be a leftover of 2011. Should I remove this registry folder before uninstalling Trados? I would appreciate if anyone could assist me in this regard.

I just uninstalled and re-installed Trados and Trados Analyse, but nothing is changed...It seems the registry "SDLX" has nothing to do with the problem. If anyone has encountered the same phenomenon, I would greatly appreciate your help.