I struggle with frames for subtitles

Hi,
I've wrote a piece for choir, and it's composed of 4 little songs. I want to add subtitles for each parts, that are at the start of new pages. However, 2 times over 4, the text frame is stuck at the end of the preceding page, whatever I do. I've tried to select every note to add the text on, but it doesn't work. I gave a simple example in my linked file. Please help :D
Thanks