The Live, Test, and Sandbox modes can only be adjusted at the account level, meaning that all pages inherit this setting. However sometimes it's needed that after an account moves into the "live" mode, for a specific page to be setup in "test" mode. Unfortunately, individual pages cannot be setup in the "sandbox" mode, but specific pages can be turned into "test" mode.
To enable test mode for a specific page, include the optional parameter "forceTestModeOn" in the url for the donation page. For example, if your donation page url is (note: this is an example link, not a real link),
You'd add the parameter to the url as,
It's important to note that the first parameter is prepended with "?" and all subsequent arguments are added with "&".
Please note, that it is your responsibility to ensure the parameter is removed when ready to take the page live.