Which section are you clicking on that won't let you go forward?You can try refreshing your browser/clearing out your cookies:
https://ttlc.intuit.com/replies...
If you have already filed, you'll need to amend, this should help guide you through it:https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-...
You'll want to reach out to your employer to see if they publish it online. If they do, you might be able to import it, here's more info on that:
https://ttlc...
It sounds like you're right, the w4 might need to be changed. Here's a calculator that can help guide you on how to change it:https://turbotax.intuit.com/tax-to...