Only on my client's PC (with at least Chrome), when they create a post and type a URL into the Page Links To: field (to replace the wordpress permalink with the link they want) it works fine. When they go back to edit that same post the permalink stays as the external link they typed in, but the Page Links To: field on the bottom is blank (it doesn't re-populate with the URL they entered the first time).. so when they push Update the permalink reverts back to the wordpress permalink. In order to save the external link they typed in the Page Links To: field the first time they have to edit the post, copy and paste the url from the top Permalink section back into the Page Links To: field at the bottom.
I've tested it on every browser on my machine and it works fine, when I edit the post the Page Links To: field re-populates with the external URL that was typed in there the first time, so when I make a change to the content area and push Update, it saves the external URL as it should.
Two plugins that I know they use for Chrome are Evernote Web Clipper and Sprout Social, but I've installed the Evernote Web Clipper on my Chrome installation and it doesn't seem to effect this issue at all.
Naveen Chand answers:
On your client's PC, try to clear the browsing data in the Chrome. Particularly Empty the Cache, Delete Cookies and other site and plugin data. Use Chrome Settings > Tools > Clear Browsing Data option in your client's chrome browser.
Also try to use other browsers on the same PC (such as internet explorer or mozilla firefox) and see if the problem still exist.
You also need to close the browser and open it afresh after emptying the browsing data.