How did you add your project title? If you entered it directly on page 1, that will have created a page override, meaning subsequent changes won’t affect that page – it’s “locked” into place as it was when you last edited it.
In Engrave mode, if there’s a red triangle on page 1, it’s overridden. See here for how to remove the override.
The token that’s on the first page of music by default refers to the project title field in Project Info. Here are diagrams showing the information that appears on pages automatically and which tokens they use.
PS – if you want the last system of all of your flows to span the full width of the page, see here for the setting that controls the horizontal justification of the final system in each flow.
PPS – Just checking that to make all the flows just show their flow number, you edited the Default flow heading, rather than manually removing the flow title for each flow? You can also delete their flow names/titles entirely, as it looks like you might have done, but editing the Default flow heading and making sure that only contains the information/tokens you want to show in flow headings gives you all sorts of options in the long run.
Unfortunately in Dorico Elements, you don’t have access to the Pages panel and so can’t remove overrides. If you’re comfortable sharing the project here, someone might be able to remove the overrides for you and send the project back.
Because you have Dorico Elements but don’t want to show flow titles in flow headings, only the flow number, your method of leaving the flow title field blank is possibly the simplest. (Because in Elements you can’t edit the formatting of the flow heading “template”.) However, having seen projects where users have deleted instrument names when they really simply needed to hide staff labels, a bit similar to this, I wanted to make sure you understood the hows and whys of the functionality so you can utilise it all fully.
Customizing page templates and flow headings are a Pro-only feature, really; manually changing the contents of individual flow headings on pages in the music will also produce page overrides.
The curly brackets and @ symbol formats are tokens: they’re the bits that auto-populate with whatever is entered into the corresponding field in project info, or elsewhere – like the layout name token that displays the layout’s name.