Hi CynthiaM95,
Thanks for reaching out to Apple Support Communities. It sounds like you're having an issue with entering characters with accent marks on your Mac. We're happy to help.
Does this issue occur in any app or a specific app? If any app, does the issue occur when booting your Mac to safe mode? The steps in the guide here can help you test: Start up your Mac in safe mode
If the issue doesn't occur in safe mode, boot your Mac as normal and test again. Also, let us know if the issue is present when testing using Keyboard Viewer: Use the Keyboard Viewer on Mac
We look forward to hearing the results.
Cheers!