thunderbird always asks for passwords on startup

Do you want and do you use the Google calendar? If so, you must authorize Thunderbird to access it on Google's servers. When you first set up your Gmail account you are asked if you want to include calendars and address books, though it's easy to miss the prompt.

If you don't want the calendar, you can unsubscribe from it on the Calendars tab. See attached image

Thunderbird has always had authorization for google calendar...i believe you misunderstand the question....now after closing thunderbird, or after a PC restart...thunderbird asks for all the email passwords and authorization to google as if you were setting up thunderbird for the first time....this never used to happen

Google uses OAuth for authorization, which may insist you re-authorize from time to time, especially if it considers you to be using a new device. Software upgrades can appear to be new devices.

Do all your accounts, folders, messages etc. still appear in Thunderbird's folders list?

You must have Thunderbird set to allow cookies for OAuth authorization to work. See <Settings | Privacy & Security | Web content | Accept cookies from sites>.

This has nothing to do with google...i do not do my email from google on thunderbird....these are all comcast email accounts....every time i restart the pc or close thunderbird....it asks me to manually enter the passwords for my comcast email accounts which is like a new set up every time...and yes i check the box that tells it to remember becasue after the initial time....its ok after that until the next update, restart etc

You started off talking about Google Calendars. Now you are talking about Comcast. Which is it?

Comcast also uses OAuth2, so the same factors apply there, too.

Please answer my questions about cookies and whether your accounts are intact.

I use google calendar on my android devices and on thunderbird so they sync....I use comcast email on thunderbird....unless thunderbird is deleted or reinstalled on my pc it only asks for passwords on initial setup....now if my pc restarts or i close thunderbird competely and then restart it later it acts like a new set up and wants me to re enter passwords....this did not happen before...after any pc shutdown...you restarted thunderbird and just moved on like nothing happened

So it DOES have to do with Google, as well as Comcast.

Please answer my questions about cookies and whether your accounts are intact.

Please quote the exact error messages and password prompts you see. Screen shots would be best.

If it is acting "a new set up" there would be no accounts or folders listed in the Folders pane. If it just wants to be re-authorized, they would be still listed.

Reinstalling Thunderbird is unlikely to affect this kind of thing because all of your account information and preferences are stored in your Thunderbird Profile, which is separate from the program itself.

Here is an article about Profiles, what they are, where they're found, etc.

https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

Actually I just discovered the issue myself....I did not have the default box checked for thunderbird email and google calendar...i have tested this and now it works fine....thank you for your time