[The below can be done in an excel file / google sheets file or CSV file]
This process is pretty simple to do. First have your .CSV file open.
All your words should be in Column A of your file of course. In "Cell B1" enter this =upper(A1).
Now hit the enter key so it shows the result.
Now you need to repeat this formula all the way down the column, click the small handle on bottom right and and drag it until you have reached the end of your words.
You should see every word in upper case.
Now right click on "Column B" and click on "Copy".
Now right click on "Column A" and click on "Paste Special" (the oaste symbol with 123 on it) or you can click "Paste Special", and pick "Values".
This is how it will look.
You are almost done now, just click on "Column B" and right click and pick "Delete".
Then press "Save" and you are ready to use it in your word search.
If you only want the first letter of your word in upper case you replace =UPPER(A1) with =PROPER(A1) in the first step then continue following this.