You can edit several terms at once to speed up global changes.
Select the terms you want to edit and click Edit selected in Manage Grid.
Verify that the right amount of terms has been selected
You can see the level of each field
You can see the field name
This is the column for your future values
Activate the checkbox for fields you want to change
Here you can either type the wanted value or select a picklist value from a list
Apply or cancel your changes at the end
Changes done here can have a huge effect on your TermBase and change a lot of data. The changes cannot be undone. Ensure that what you are doing is correct. It is recommended to create a backup of your TermBase before bulk changing any data.