I have to change the color of all the objects in all the sheets of a document, so I change the color in the active/inactive header settings (tag Header in Documents Propriety) and the color of the cursor bars and the borders (tag Presentation in the Documents Propriety), but all the object of the sheets didn't change at all (as I expected).
The second problem is that I'd like to change the tag color setting of all the sheets, but I didn't find where I can change this parameter in the global setting: have I to change this color sheet-by-sheet?
Q1: Document Properties->Caption sets default values for all objects created subsequently.
You can use themes to change colors globally. See Object Properties->Layout for "Theme Maker" and "Apply Theme" buttons.
Q2: With "tag", do you mean "tab" of a worksheet? In that case you can change the tab color for a single sheet in Sheet->Properties->General->Tab settings, and propagate those new colors to every other sheet by clicking the "Apply to All" button.
I tried to make as you suggest for the Q1 and I create a Theme ad hoc with the characteristics that I'd like to set, but when I apply it on another document, only the sheet background and the tag setting are replaced; the active/inactive header color setting, the border color setting and the cursor bar color setting are not replaced.
Note that in the color theme wizard I specify all the properties to be included on the theme.