Replacing text in document at MS Word is so easy as you can image, just follow some steps...
Step 1: Open Microsoft Word Application.
Step 2: At the top from the right ribbon click "Replace" button which is at the "Editing" group.
Step 3: After clicking the "Replace" button will be open a new window named "Find a Replace".
At the first field named "Find what:" write the text that is in your page that you want to replace with other text.
At the second field named "Replace with:" write the text that you want to replace. After writing two fields we need to choose which way we want to change the text, one way is to change one by one the other way is to change all by one. The button "Replace" is one by one the button "Replace All" is all by one. Click which way you want to replace or change the text.
You can do the fast way be shortcut click Ctrl+H and the window will be open and write down at two fields and click one of buttons.