How do I set a default theme in VScode theme?

I installed new themes in my VSCode IDE, but every time I close and reopen the IDE, the theme reverts to the default theme, and I always see this pop-up box at the bottom right corner of my IDE when I reset the theme that says:

Unable to write into user settings. Please open user settings to correct errors/warnings in it and try again

When I open the user settings, this is what I see:

{
    "workbench.editorAssociations": {
        {
            "viewType": "jupyter.notebook.ipynb",
            "filenamePattern": "*.ipynb"
        }
    }
    "kite.showWelcomeNotificationOnStartup": false
}

{

"r.bracketedPaste": true,
"r.rterm.windows": "*Path to radian executable*", //C:/Users/IFEANYI/anaconda3/Scripts
"r.lsp.path": "*Path to your R executable*", //C:/Users/IFEANYI/anaconda3/Lib/site-packages/pyls/__pycache__/lsp.cpython-38.pyc
"r.lsp.debug": true,

}

I don't understand very much what is going on here. Can I delete this setting and let VSCode generate a new default setting?