On Intel, you choose the BeOS volume that you boot from (the boot volume) by using the BeOS boot manager, Bootman, which runs at the end of the installation procedure.  See the Installation Guide that comes with this release for more information on Bootman.

On PPC, you set the boot volume by using the Boot preference, described below.

Note that using Boot to set the boot volume is only meaningful if you have the BeOS installed on more than one volume or disk. Boot's Easy/Expert popup lets you choose the boot volume by name (Easy) or by its bus address (Expert).  If you're booting from a SCSI hard disk, leave the LUN: (Logical Unit Number) set to 0.