Several editing features of the project are limited if you are not the creator, depending on the access rights given to you. You can rename a project only if you have created it, or if you have administrator rights.
Projects shared with you and of which you are not the creator are indicated by an arrow to the left of the project name (in the menu bar on the left).
To see what your rights are, go to the project settings: Project> "Settings" icon in the top right corner of the window. Go to the "Collaboration on project" section. There, you can consult the list of members having access to the projects, as well as their rights.
To learn more, see the article dedicated to project sharing and access rights.