In your previous article on how to add a quota you have successfully created a quota which you want to edit now.
Start by selecting your quota. Click on the selection box in front of the quota row, click on the action button and select Edit.

The edit quota row window will appear.

You can edit the following fields:

Fill in your quota number.
Start Date
Select the start date of your quota.
End Date
Select the end date of your quota.
Select the users to add them to your quota.

After editing your quota click on update to finalize your actions. You are finished editing your quota.

See our article on how to delete quota to remove them.