How do I make sure no one is signed into my iCloud account on another divice

Hey BigDlittleC,

That's a great question! You don't mention which device you'll be using to check, so we'll provide the steps to check using an iPhone:

Use your iPhone, iPad, iPod touch, or Apple Watch to find where you're signed in

1. Tap Settings > [your name], then scroll down. 

2. Tap any device name to view that device's information, such as the device model, serial number, OS version, and whether it's a trusted device that can be used to receive Apple ID verification codes. The information might vary depending on the device type. You might need to answer your security questions to view device details. 

The above steps and more can be found in the following guide. The guide also has steps to check using other device or the website, and steps on adding or removing an unknown device: Check your Apple ID device list to find where you're signed in - Apple Support

Thanks for using Apple Support Communities.

Take care!