Let's try changing an item that is attached to the template:

1. Open Configuration | Templates, select Custom templates from the Group drop-down and click on Items next to C_Template_Linux.
2. Click on SMTP server status in the Name column. As we can see, all fields are editable when we edit a directly-attached instance of an item.
3. Change the History storage period field to read 14d, then click on Update. 

When an item is updated in a template, the change is propagated to all linked hosts. This means that with a single action, both linked hosts have their history-keeping period set to 14 days now. But we changed two item properties for one downstream host before, and we just changed one of those for the upstream template. What about downstreaming the host's other item? Let's find out:

1. Go to Configuration | Hosts, choose Linux servers in the Group drop-down, and click on Items next to A test host.
2. In the Name column, click on SMTP server status:

We can see that our downstream change for Update interval has been preserved, but the History storage period value has been overwritten with the one set for the template. That's because only changed properties are set to downstream when editing template-attached items. Now click on Cancel.