With the navigation you have overall control of your song. Settings you perform here may influence the behaviour of AGS. There's a duration label doing a time approximation. It is really unreliable and may differ about 30 seconds after 3 minutes of playback. Note with higher frequency of the audio related threads it may differ less. An other factor is bpm what has an influence, as well.
The beats per minute (BPM for short) indicates the velocity of a song being played. To adjust the BPM of the project in-/decrement the spinner labeled with bpm. To edit patterns or notes at a more granular rate select the wished tact within the appropriate engine or editor.
To calculate timings you divide 1 minute with the entered BPM and divide it with basic. For example you have a BPM rate of 120 and a 4/4 tact you would calculate the timing as follow: