Minecraft Launcher requires sign in when launched

You should have the option of staying signed into the Minecraft Launcher. If the Minecraft Launcher is working for you, but it tells you to sign in every time you start it, try cleaning up your cached account tokens. Follow these steps:

Clear cached account tokens

1. In the Launcher, click Settings.
2. Click the Accounts tab.
3. Click the Advanced Options at the bottom to open it.
4. Select Clean up cached account tokens.