You might have several assets that you want to edit in bulk. For example, you might want to update replacement cost for a group of devices. You will do this from the asset list which you can find under the "Asset List" tab in the left hand navigation.
Select multiple devices with the check boxes in the left column or select all with the box at the top of the column. Then click on "Choose an Action" dropdown.
Select the field you would like to update from the dropdown.
A modal will pop up with a count of how many assets you have selected to update. Enter the new information and click update. This will immediately populate in the asset list and reporting.