My project currently has 68 pages and 15 flows. I would like the First template to stay on the first page of each flow–I have the layout settings set to New Flows Always start new page and Use 'First" page template: Any flow starting at top of page. But if I make layout changes that alter the page layout, the First page template doesn’t stay on the first pages of each flow (it stays on the assigned page number instead, which after layout changes is no longer the first page of the flow). Is there a way to “lock” the First page template to the first page of the flow, rather than the page number?
Welcome to the forum.
Making changes to the layout of a page breaks the link between the template and the page. If you modify page 54, then page 54 will stay as it is, until you remove the override.
It’s therefore strongly advised not to make such changes until the last possible step in the layout process. What changes are you making? Might there be a way to make them without creating a page override?
Thank you for the answer! So far I’m still experimenting with my preferred vertical staff distance settings, and since some of the pieces have different scorings (2-6 staves, depending), I’ve adjusted it to suit the different scorings as they arise (for example, to get three systems on a page for the 4-voice systems, but not squish the 6-voice systems too much). However, given your advice, I’m going to stick more closely to the default vertical spacing, at least until the last piece is done. Once I have the “first” templates where I want them for the full score layout, is there a good way to get them to appear on the first page of each flow for the other layouts? I’m going to print out a short score (just the 1st violin, voice, and continuo), and one part each for violins 1, 2, viola, and trumpet.
Unless something has changed radically, that should not happen unless you have assigned the First page template manually rather than using the Layout setting that will assign a First page template automatically to the first page of any new flow that starts a page.
Unless, that is, you have other overrides on the page. It would be interesting to see an image of the right-hand panel of your music in Engrave mode to see what that shows.
Thank you! Yes, I did indeed assign templates manually. Having done that, is there a way to reset all the pages after the fact, so that the first template is automatically reassigned back to the first page of each flow again? I’m thinking, from BenWiggy’s answer above, that the answer is probably no.
You can remove all Page overrides by right-clicking on the page icons.
You can set the Layout Options to use the “First” page template on the start of each new flow.

