Hi Kevin,
Welcome to the forums.
In relation to the slurs, have you tried the following ...
1. Right-click on the starting note and select "Notation Options | Slur".

2. When the next dialogue box pops up, tell the notation how long you need to have the slur last (i.e. its length). To do this, you need to enter a value for "Beats" and one for "Ticks" - keeping in mind that 120 ticks = 1 beat.

3. I created the following slur by entering Beats = 2 and Ticks = 1. That is, the slur covers two full beats and then finishes on the note on the first tick of the third beat.

There are many unique features in BIAB that require developing an understanding of how they operate. Notation is probably at the top of the list because BIAB notation is very different from usual notation programs.
Hope this helps,
Noel