I recently downloaded the windows 10 beta. I get to the screen that tells me to sign in with my xbox live account, so I do, then it jumps back to minecrafts main screen that has the play button and says to sign in. Everytime I click play, it signs in, then loops back to the main screen again. How can I fix this?
I'm going to assume that you're having issues with logging into Xbox Live.
Open the Xbox app, and go to the settings pane and look for the "Sign out" option -- select it, and restart your computer. Once you've done that, open the Store and press your profile icon which should give you an email.
Launch Minecraft, and it should ask you to sign in to Xbox Live. Press "Play" and it should take you to the Xbox app, login with the exact same Microsoft account that you're logged into the Store with. Close Minecraft, open it again and check if it still asks you to sign in.
If it does, right click the taskbar and select "Task manager" and go to the Services tab, sort them alphabetically by name and go to the bottom. While Minecraft is open, what are the statuses of XblAuthManager, XblGameSave and XblNetApiSvc?