Takes forever opening Thunderbird and when selecting account settings it hangs up

Every time I start Thunderbird it takes several minutes and sometimes doesn't start up. Once it does open up, emails do update new ones but if I go to account settings and select anything it hangs up. If I click on it, grays out and gets a message Thunderbird not responding. I have to open task manager to stop the program. Why aren't the emails on my email server get deleted/ moved updated when using Thunderbird? It seems like the only thing that happens only gets changed on the device I made changes to only. (computer, or phone or laptop)