There are many flows in my suite, I would prefer to have the parts reflect the flow name rather than the layout. Currently the token is {@layoutName@}, how can I replace this with {@flow2title@} globally?
Go to the Page Template (in Engrave Mode) and replace the token there.
H’mm when I replaced {@layoutName@} with {@flow2title@} on the Page Template in Engrave, the name of one flow was on top of all the flows. “Mvt. 1” was there even in “Mvt. 2” etc
Do you have Flow Headings switched on in Layout Options?
should Flow Headings be on or off?
It’s up to you? If you want an automatic way to have the title of your flow above each flow (in a particular layout) then have it switched on.
You can edit how it appears (the token etc) in the right panel (underneath where you double clicked Page Templates etc).
I don’t use them.
Also, I forgot to check if you have any Page Overrides on any pages? There should be a little red triangle in the Pages panel (just above where you double clicked Page Templates!). An override will not necessarily show what is in your template.
{@flow2Title@} is explicitly for Flow 2. If you want the current Flow for that page use just {@flowTitle@}.
I didn’t even think of that 
The Layout token normally appears on the first page, and shows you things like “Full Score”, “Percussion”, “Trombone 2”, etc.
The Flow title will give you the title of the flow, e.g. “Danny’s Theme”, “Overture”, “Act 2”, etc, which will be the same for every part and score. (Unless some players are not in some flows.)
I’d suggest that these two tokens represent different things and are not really interchangeable. It’s usual for parts to display both of them, as they are both useful information. How will you tell which printed part is which?