How to Set which Diary displays first when logging into HP

From the Lookup Button select Practitioners at… your clinic.
Double click on the Practitioner you want to display when first logging on.
Ensure The Primary practitioner when first opening the diary is ticked, as below:

Click OK to Save.
Note you can also change the order of the practitioners as you want them to display in the bottom right hand side of this window. Click on the Practitioner in the little table and then click the up or down arrows to the order you want the practitioners to be.