Tablatures allows to change the beaming pattern on a per-bar basis. The pattern is defined in the Time Signature page of the barline properties sheet:

Editing the beaming pattern (click to enlarge)

There you would enter the number of 8th notes to group together. In the example, you can see that entering 2 will result in groups of four 16th notes (which are equivalent to two 8th notes).

When you add a new barline, Tablatures will automatically copy the settings of the previous bar.

The usual culprit is the lack of a Guitar In symbol at the start of the document. Tablatures uses Guitar In’s to determine which instrument (as defined using the Score -> Edit Guitars menu) should be used for playback.

When you create a new document, Tablatures already puts a Gtr I symbol at the beginning.
If you delete it or need to change instrument in the middle of a song, adding a guitar in symbol is very easy to do:

1. Tick the Guitar In checkbox in the Musical Symbols Panel:
   
2. Then choose the guitar(s) which should be start playing from the current caret position:
   

Finally, you might want to make sure that all the guitars you have used are actually defined among the instruments used by the score. So let’s use the Score -> Edit Guitars menu and edit them as needed:

Here you can choose the MIDI instrument to use, apply some effects and change its tuning.

By default, new documents are set up for guitar and bass, since it’s the most commonly used configuration, but in a few click you can customize the score to satisfy your needs.

First, you can change the number of tablature lines to match the number of strings of your instrument. To do it, click on the vertical TAB text at the beginning of the system:

A sheet that will let you choose the number of strings will appear:

This settings will be remembered when you add a new section.

Next, let’s define the properties of the instrument to be used for MIDI playback. Use the Score -> Edit Guitars menu:

Click to enlarge

There you can choose the MIDI instrument, define the tuning of its strings, apply some effects and so on.

That’s it, now you’re ready to compose your song.

“I cannot seem to figure out how to, for example, put down a whole note on one string of a quarter note on another *that start at the same time*. This makes it impossible to create a base line for a piece of music that isn’t played exactly on beat with the treble part of the music.”

Tablatures allows you to write your high and low melodies independently, thus you can achieve what you need in the following way.

Let’s start by adding a note to the high melody:

Then, in the Notes Panel, we switch to Low melody, change the duration and enter the second note:

That’s it.