I'm in the middle of migrating to a new laptop (WIn 7 Pro to Win 10 Pro). The old one has TB 68.10.0, with Lightning. When I installed TB on the new laptop, it gave me 78. I had copied the profile folders already. I'm having trouble with the (Google) calendar. First, it gave me no data/didn't sync and wouldn't let me do anything. I also tried importing the old one just to see, but that crashed TB. I tried unsubscribing, but that removed the calendar. I tried setting it up the old way, New, Network and pasting in the private Google link. It keeps reverting to Read Only, every time I try to do something. Then TB hangs up, doesn't display properly, and there's no response for several minutes when I attempt to close it. I want to go back to the version that is on the old laptop, but I can't find downloads for any previous versions. Where are they?