I have just noticed that if I change the date of a diary entry, the old date still shows in the Agenda side bar. Surely this shouldn’t happen or is there a setting that needs to be changed somewhere?
Thanks
Ray
The Agenda side-bar is one of my favorite features in eM Client. 
This issue may depend on where you changed the entry, what the sync settings are, or even the type of calendar you are using. If, for example, you change an event on your phone, and eM Client is set to sync every 20 minutes, then it might take that amount of time before it shows up in the side-bar. Unless there is some sync error, then it won’t change at all.
But if you change the event in eM Client’s calendar section, it should immediately be reflected in the side-bar.
There has been an issue with some areas refreshing in recent versions of eM Client. Maybe that is what you are experiencing. Though it is not a solution, if you restart eM Client, is the change reflected in the side-bar?
What version of eM Client are you using? (Menu > Help > About)