Two of the most important settings are Title and Menu entry. Their function is fairly self-explanatory. They may be identical, but, often, the menu entry is shorter than the title.
Carrelet provides the facility to override the page layout and appearance settings on a page by page basis. This can be useful if, for example, you wish to have a page of 'small print' that needs to contain a lot of dense text, or if you want a sobre colour scheme for a particular topic (eg a staff obituary).
However, it is generally good practice to keep pages at any one level in a website fairly consistent. In particular, the font and layout settings should not usually be over-riden.
Also, choose the use global setting option rather than the specific choice that you made in global settings. This means that if at a later date you change the global settings, you will not have to modify every page in the site, as they will all pick up the new settings automatically.