How to Solve a AD Connect Synchronization Services?

Hi, 

 

please follow the link :-  https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnectsync-change-serviceacct-pass

 

and another  one for  better  understand :- 

 

https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect