Форум поддержки Thunderbird

Only in the last 24 hours,I cannot add Attachements to emails I downloaded Microsoft Iview & that change Preferences on a lot of Apps Below is a examaple of it,I have tried different PDF Readers & they all do the same If I Go To The actual Folder in D Drive,then they will all open ok Please assist Thank you Darryl.Smith

D:\SCAN DOCUMENTS\D & L Smith new Certified Id Documents 2023\ID Ds Passport 2023.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.

how do I change the "from" and "subject" font appearance in thunderbird inbox list view? They are currently a little bizzare with the sender appearing smaller than the subject line etc. I am not familliar with .css file settings and so will need to be considered a simpleton with any explanations. Any aswers I have seen refer to fire fox and assume that I know how to create the changes required or add a .css file somewhere. Thanks in advance. I attach a screen shot of my current inbox view . Hope this explains my problem.