@likit sorry you feel that way.
The issue was with Yahoo and eM Client provided a workaround for the Yahoo autho problem where at that time you had to manually enter the details via the “Other” mail account option in the setup.
See the following thread below and particular comments from @Olivia_Rust eM Client support.
Since then Yahoo has fixed the autho issue and eM Client then did another update sometime ago which then connects again via the normal automatic email account setup.
See official eM Client blog on the 24th Nov below.
Lastly as @Gary advised If you have a Pro License, please open a support ticket with eM Client to get this resolved if still not working.