I have just updated my apple to mojave and ever since then 9 out of 10 times when trying to attach a document or picture I am unable to select it. The screen just freezes and all I can do is 'maybe' move the window around. I have tried to download the latest version of Thunderbird. Sometimes it indicates that the latest version is installed and others (when I go to Thunderbird and hit 'about thunderbird' it will indicate the out of date version) What am I doing wrong?