It's not the highest numbered baseline that shows up by default, it's the
one and only baseline. Project has 11 slots for baseline data, labeled
Baseline and then Baseline 1 through 10. As far as the Tracking Gantt chart
and all the other areas where baseline and vaiances are shown, the baseline
referenced is the one labled simply Baseline without a number. If you just
"Save Baseline" in the menu, that's the one that gets saved or overwritten.
If you want to save it into one of the vacant 1-10 slots, you need to
specifically set that as the destination.
IMHO, a given project has one and only one functional baseline that is fixed
in stone at the time the initial plan is approved and it should never be
revised or updated from that point onward. It is the sole record you have
of 'the plan we intend to work.' The only exception to that rule is when
tasks have been added or removed from the plan so as to change it into what
is essentially a new project, hence the plan has become a new plan. The
numbered baseline slots, Baselines 1-10, are to provide for the capture of
an audit trail to monitor the changes in a dynamic project that is
essentially changing direction over time with tasks being added or removed.
Variances in performance against the original plan without having tasks
added or removed should NOT trigger revised baselines since that in effect
wipes out all record of your variances - it's tantamount to saying 'No
matter how it compares to what we originally intended to do, we'll just
pretend that whatever happened was what we really wanted to happen.'
HTH