When you visit a date for the first time, we copy the company/addresses over from the prior log. This generally works really well, except for the case where you have the wrong company or address, and then visit new dates, and the incorrect info is copied forward. Then if you want to change it, you have to change it manually for every day you visited. There's really no way to tell IN ADVANCE of viewing a day, if you've viewed it before. The best way out of this situation is to simply correct it on each day as you move forward. Eventually you'll visit a day that hasn't been viewed before, and it copy the correct info from the last log you just viewed. Just stay with it!
Truck/Trailer/Codriver/etc. all are copied when you visit one of those fields (by clicking on it or tabbing to it).
Hope this helps!