Welcome to the world of BIAB.

The meter is determined by the style you choose. Good way to start is to use the Stylepicker button (Ctrl F9). On the left side you will see Categories of the styles. Towards the bottom are Waltz and 6/4 categories. Click on that and on the right you will see the different styles. You can sample the style by clicking the style and hit the Load Song Demo button. There is also a search feature (Search Button) that, where entering a song, may find a style matching that song (ex: Moon River). That should get you started.

One other thing is when entering chords in 3/4 time, beats 1 and 2 are in entered in the first cell and beat 3 the second cell. C [enter] G [enter] will play the C on beat 1 and G on beat 3. C,AM [enter] G [enter] will play the C on beat 1, AM on beat 2 and G on beat 3.

Have fun.
R