removing/changing fields names in extended tag window

I have an extended tag field I would like to change; the year field to date. Every time I do this, the year stays & the date filed is not added. I open the extended tag window, click the year field, & change it to date, but when I view it in windows, the year filed is still there & the date field that I added is not. But it shows up when I change year to year-Date. Can fields only be added to? & not removed renamed replaced?

Yes, it is a two-step-action: first copy the data from one field to the other and then delete the superfluous field.

The good news is that MP3tag supplies actions to do just this:
Create an action of the type "Format field"
Enter date as target field and %year% as pattern string.
Then add an action of the type "Delete field" with YEAR as the field to be deleted.

I am not sure I completely follow, I went to quick actions along the top & there was a drop down option of format value, but I did not see format field. So I chose the next closest available option; format value; then I selected year & the %year% pattern string. This did something, but it did not seem to change the year field name to date. I then went back to the quick actions menu, but there is no option for delete field among the drop down options. So I chose the closet to this; remove field. But it does not seem to be working, the year field stays. In windows as well, nothing seems to be changing. When something does happen, I see a doubled year field with the date/year in the extended tags window.

Do media players like itunes,windows media player, mp3 players & ipods only read a date/ and or year if they are preceded with the word year as the field name?

Is the quick actions the right place to go to? how do I create an action? I don't see this option. If you could provide a visual this would help.

No

Press Alt-5
A subdialog will open. This is the dialog that holds all actions and provides the function to execute, create and edit actions.

On the right there is a "New" button.
To create an action, press this button. Enter a reasonable name in the following dialog and press OK.
Then select an action type. What you have to do in your case is described in my previous post.

Although the question has already been answered by ohrenkine, this FAQ entry is an almost perfect match to your question: How do I create a new action?