How to replace repeated Variables in MS OFFICE

For New Document

Step 1: info > properties > advanced > custom > create > add

Step 2: insert > quick parts > field > select your custom field > select OK

Step 3 : home > dropdown Clipboard > copy and paste your customized data

Now whenever you want that text click on the clipboard it will pasted and to update just go back to step 1 change the value it will replace the whole text with updated one.

For existing one:

Better to use find and replace feature via CTRL+F