Hi Ruth - hope you're well.
Find a document using explorer - right click the document and choose "Open with" item in the menu that pops up
A new window will open up, which gives you the various programs you can use to open the file - it will normally include Libre and Microsoft office programs (ie Writer, and Word).
Choose the one you want, and ensure that the box bottom left is ticked (Always use the selected program to open this type if file).
Then click OK and the document should open in what you selected (Word in your case)
There may be an intermediate menu at the end of the first line which contains the various programs and a Choose Default option - if there is choose that and it will then go to the next line as above.
You may need to do the same routine with Spreadsheets and Presentations if you use them.
If that doesn't go quite right for you, give me a call and I'll talk you through it. Sunday is fine for calling - Monday I'm out some of the day.