Just double click on the value that you wish to edit.
Make the changes that you wish to make. Then hit your Enter key or click on another field to save your changes.
You can add to the list so you can use in the rest of the application. Just scroll to the bottom of the list and double click on the blank field.
Type in the new primer type that you want to add to the list. Then hit your Enter key or click on another field to save your changes.
If there was a primer type that you wanted to get rid of since it was not in use, All you have to do is click on the column beside that value that you wish to delete to select it.
Once you have the value selected, just hit your Delete key to delete the value from the database.