All six vowels are always available, and from the main filter window a preset stores all of them, their formants and the sequence information.
When actually in the formant editing window itself you only store the formants of the currently selected vowel as a preset. No other data at all.
Even though you may only have three or four formants per vowel enabled and active, Yoshimi will store (and recover) all twelve possible formants per vowel. Initially formants have fairly random settings for 'Freq' 'Q' and 'Amp', but once saved these values become fixed.

Only the number of vowels selected will be active. This is complicated by the fact that the sequence doesn't have to be of any specific vowels in any particular order.
For example; if you have a sequence size of three vowels then these could be 5, 1, 3 in that order, or even 4, 2, 4. Yes, the same vowel can be used in two places.

Another trap for the unwary is that you can still edit vowels that are not currently in use... and wonder why nothing seems to change. There is now a warning of this in the form of a redish patch that appears behind the vowel number if it's not in use, i.e. not seen in any sequence position.


