Are you are using a non English version of Thunderbird.  What language identifier is in the link that opens?  The one I posted is en_us  but that language is generally picked up from the operating system locale and the IP address the server it accessed from, therefore the link opened can be different with regards to language to Thunderbird. The  language information is determined in the browser, not Thunderbird.  The link it passes to the browser in this instance is https://support.mozilla.org/products/thunderbird and the web server allocates a language into the URL based on your browser settings

1. Change the spacing how? Insert a paragraph after enter you change the style to an from body in the toolbar where it generally either says paragraph of body. 2. Alt+1 on the keyboard. Or right click a tab and tell it to close all others. It will not close the inbox tab. So you are never more than one click away form the folder pane with inbox 3. If I recall correctly there is an addon that does that. Personally I do not want it to assume anything for me. So really It is not something I know about. I am not even sure which folder I might be interested in when the program starts. If depends on which get new mail after the program starts. 4. What scrolling text. Do you mean tabs where you have perhaps every email you ever double clicked on open to read still open. For a cure see 2. 5. No idea. It open this page for me in Thunderbird 140.6ESR https://support.mozilla.org/en-US/products/thunderbird That page also opens whenever you press F1 anywhere in Thunderbird, not just when the menu is showing. Could it be you have some sort of issue with your software firewall that is blocks the link in Thunderbird. Try navigating to the addons and themes on the menu and search for theme in the search box. Do you get a returned result showing some themes you could install or some sort of error. Are you are using a non English version of Thunderbird. What language identifier is in the link that opens? The one I posted is en_us but that language is generally picked up from the operating system locale and the IP address the server it accessed from, therefore the link opened can be different with regards to language to Thunderbird. The language information is determined in the browser, not Thunderbird. The link it passes to the browser in this instance is https://support.mozilla.org/products/thunderbird and the web server allocates a language into the URL based on your browser settings