After I changed my Thunderbird password on one of my email addresses Thunderbird tells me Login failed and asks for a new password. How can I fix this?

I changed the password for my email address on my host server and entered that new password when Thunderbird says I cannot login and asks me to change my password. I change my pw and check the box asking me to save my pw in the Password manager. Then I will not have a problem getting email but a few hours later I get the login error again repeatedly even though my new pw matches that pw on my host account. I never had this problem before I updated my password. I am using Mojave on my iMac. I have been looking for solutions all over the internet but nothing has worked. I tried removing the pkcs11.txt from my TB folder. It seemed to work at first but now I get the login failures on my smtp email account over and over again. What can I do to stop this?