If there are many assessments that are to get a new tag or changing an old tag you can use the mass update function. Check off the box to the left and click on Mass update tags on selected.

Choose a category from the drop down menu before you move on further and choose an option. Click on the Save button to save your choices. Notice that the number of sections you are to change the tag on will be shown above the drop down menus for categories and options. 

NB! It is important to be aware that if you happen to check off the upper box you choose ALL of the tasks. Be careful and make sure you only update the correct amount of tags.