Yes, if you are submitting a Word CV (also commonly called a resume), you should make it read-only.

Making your CV read-only in MS Word or Google Docs ensures that:

• Spell-check does not leave red lines on your CV
• Your resume formatting stays how you want it
• Hiring managers cannot accidentally edit your CV or delete a section

Alternatively, you can save your CV as a PDF file to submit. Resume PDFs can’t be edited easily and hold all formatting.