The Bass Box is usually tuned in a circle of fifths- looking down from left to right the notes are F,C,G,D,A,E,lowB. Some folks like the A tuned down an octave also- F,C,G,D,low A,E,low B.
Making the blade longer, by pulling more blade out from under the bridge, will make the note lower. Shortening the amount of blade will raise the pitch of the note.
Most of the time small adjustments can be made without loosening the bolts, occasionally it is necessary to loosen the bolts to make adjustments. Usually only small adjustments (less than 1/16th of an inch) are necessary to "fine tune" the note.
Once the Bass Box is "tuned in" it will hold its tune for a very long time- like a year at a time.
The nature of the Bass Box is that each note has several overtones. This can seem like a problem when playing the Bass Box by itself- but the overtones seem to disappear when playing in a group.
The Bass Box comes roughly tuned. Some electronic tuners will "hear" the bass notes and can be used to tune all the notes. Because of the overtones it is sometimes necessary to take an "average" to get the note you want. After you get a couple of notes correct one can tune the rest of the notes by ear by playing Twinkle, Twinkle Little Star ccggaagffeeddc and Mary Had a Little Lamb edcdeeedddegg.