Glitches in address fill-ins with nicknames; default font problem; plus other glitches in Thunderbird 31.3.0 and 31.4.0; can I roll back to an earlier version?

Question

I am unhappy with the recent upgrade to Thunderbird 31.3.0 and now 31.4.0. My bottom line question is whether I can roll back to the previous version, which was working well for me.
The problems I have encountered include:
1. I used to be able to enter a single letter in many cases in the address field, and the autocomplete would fill in the entry that I always use with that single letter. That function has been lost, as has auto fill-in based on the nicknames I have entered in my Address Book. I see there is another thread on this problem (https://support.mozilla.org/en-US/questions/1036962), but no satisfactory answer so far. Entering a single letter now pulls up completely unrelated address entries that may not even have that letter as part of the name, address or nickname for that unrelated address. I have created new nicknames to try to adapt to this problem, but even these new nicknames no longer work with the 31.4.0 upgrade yesterday, forcing me to create yet more complex and hard-to-remember nicknames to pull up my frequent addressees. This is all very frustrating to me, as I depend on speed and ease when creating messages.
2. Also, I used to be able to enter a single letter in the address field and then use the mouse to click on the "To:" symbol to the left of the next address line to change the next entry to "Cc:"; doing so would then cause the complete address to fill in in the "To:" address field, and make the next field ready for an entry. That no longer works. If I use that technique, the shortcut that I entered in the first field gets included along with the address (if I'm lucky enough to have the address itself selected now, given the problems I've mentioned above). I now have to press "Enter" in order to get the address in the first field to "take" correctly, and then have to click on the "To:" symbol for the next line as a separate action. Just another inconvenience with the new version.
3. While still on the subject of addresses, personally I see no reason why the address and subject fields should now be colored blue by default rather than appearing as blank, white fields. I far prefer the old look. And I suspect that changing from the blue color to a nice, clean, white field takes time and computer resources that slow things down.
4. The default font (Times in my case) no longer "takes" when replying to or forwarding messages. I've checked Tools/Options/Composition, and Times is still shown as my default font. However, when I start to type (in a reply with the original message quoted or in a forwarded message), the result is "Variable Width". In order to get Times, I need to highlight the block of text after typing, including the lead-in to the quoted message or the header of the forwarded message, and select "Times" when "(mixed)" shows up. This is a big pain; I often forget to do so and end up having to edit the Unsent Message (which I check before sending) as New and correct the font.
5. A minor problem: I rely on the reminder to attach a message which shows up when an "attachment-related" word is entered in the body of the message. It has been a wonderful feature of Thunderbird that has prevented me on many occasions from sending off messages without the attachments. However, in the new versions, even if I have indeed added the attachment, a pop-up comes up on sending the message saying there has been no attachment and asking if I want to add one. It's easy enough to just click "No", but it's yet one more unnecessary and distracting step that this new version is requiring of the user.
I'm really sad to see these various changes/glitches. I love Thunderbird and it bothers me deeply to find myself mired in so many new problems that slow down my work. I would be grateful for any suggestions and advice, and, particularly, for any information as whether I can roll back to the version prior to 31.3.0 that was working well for me.

Answer 1

Thank you, Zenos. I tried rolling back to v31.2.0, since I had not encountered problems prior to December. However, that didn't help. So I followed your valuable suggestion to revert to v24.6; that seems to have done the trick.
I would like to mark this problem as "Solved" -- the rollback seems to have worked. However, since my original post was a complex mix of things, before I do that, should I post the individual problem sets that I had noted (address fields/nicknames problems -- numbers 1-3; default font problem -- number 4; attachment reminder problem -- number 5) as separate issues which have not been solved?
Do you know if these various issues are being worked on? I'm glad to have the temporary fix of rolling back to an earlier version, but I'd like to get back on the current update schedule at some point if and when these problems have been corrected.
Thank you again!