I do not find anything non grammatical here. Unlike English, French do not capitalize every word in a title or similar.

There is a toolbar (barre d’outils) named Accès rapide and a menu to customize (personnaliser) it.

In English, this function is called “Customize the Quick Access Toolbar”.

Accès is capitalized to show it starts the proper name of an entity (similar to the title of a book, or the name of a chapter).

To better stick to typographical rules, it might have been quoted too like this:

Personnaliser la barre d’outils « Accès rapide »

or italicized:

Personnaliser la barre d’outils Accès rapide