You can choose a set of templates saved in your sandbox space by using an appropriate sandbox prefix. For example, if you want to preview a version of ꠐꠦꠝ꠆ꠙꠟꠦꠐ:Test that you have saved as "ꠛꠦꠛꠀꠞꠈꠣꠞ꠆ꠞꠣ:Foo/sandbox/ꠐꠦꠝ꠆ꠙꠟꠦꠐ:Test", use "ꠛꠦꠛꠀꠞꠈꠣꠞ꠆ꠞꠣ:Foo/sandbox" as the prefix.