OO5 beta keeps changing default "Open with"

I’m testing OO 5.0, but since it’s just a beta, I don’t entrust it with my working outlines. I open them in 4.6.1. But every time I download a new 5.0 update, it changes the default “Open with” to 5.0. How can I stop that from happening? I want the default “Open with” to be 4.6.1., not a beta.