You can recognize outdated cross references by the red flag in front of the link . Or, by going in Monitor --> Cross references --> Click on the Filter, select only outdated links --> Apply.
There you can see the list of all links that need to be updated.
There are 2 ways to fix cross-references, you can update them in bulk or manually.
1. Update multiple cross-references at once:
Click on Review --> Check for warnings --> Next to Cross References outdated, click on the wrench --> Tick the box on the left side of Page --> Click Fix.
2. Update cross-references manually:
Certain links cannot be updated with the Fix button and need to be manually updated. Go to the page where this link is by looking for that page or clicking on from the cross references panel on the left.
Click on the link --> Press the link icon in the middle --> Update link --> Ok
If you need more information on Why do my cross references become outdated? and the workaround to fix them, click on the article!