Your recent update has made the Address Books scrollbar extremely narrow. How can I get it back to a normal size?

Please look at the pictures: 1. the image "Thunderbird Address Book scrollbar is extremely narrow.png" shows the new Address Books scrollbar 2. the image "Example of normal width scrollbar.png" shows the scrollbar within a particular Address Book I can't find anything in Thunderbird that will allow me to change this. The normal width scrollbar is probably set in Windows settings. Thanking you in advance. Shirley