There are 2 issues here.  One is a fix and the other is an enhancement.

The fix applies to situation where you have multiple tenants with the same name.  This can apply quite often when you are using the rental calendar because often a tenant will come back and stay multiple times.  The issue is related to the LinkTo button and linking to Extra Charges.  Currently the system cant differentiate between 2 tenant with the same name, so if you are adding extra charges after using the Link To button the extra charges might get added to the wrong tenant.  The next version will be able to differentiate between them.  The short term solution is to always create tenants with unique names.

The enhancement is also related to the rent calendar screen.  If you double click an entry in the calendar it will now Edit the selected tenant.