Welcome to the community!
Are you getting any error messages that you can share with us? Often, not that it applies to you, but often it can be as simple as a typo or copy/paste error but if you can share some more info, we may be able to help you identify the problem.
Did you find any helpful responses or answers to your query? If yes, please mark it as the ‘Best Answer.’
A couple of common problems that can crop up with URLs is that you need to have the top level domain matching between the Display URL and the Destination URL and only 1 Display URL in each ad group.
A display URL of www.adwordsforum.com with a destination URL of www.adwordsforum.com/new would be ok, but a display URL of www.adwordsforum.com with a destination URL of www.forum.com would not be ok, because the top level domain (ie - adwordsforum.com) does not match between the Display and Destination URL.
Please also bear in mind that there can only be 1 Display URL in each ad group. If you have more than one Display URL in an ad group the ads for this second URL can be disapproved.
I hope this helps.