How do I know which block is “mine” when pairing amongst others on SAM Blockly?

You can tell the block is 'yours' based on the signal strength. Once you turn your blocks on and click ‘CONNECT’, your block appears on the screen along with a signal strength. If your block is close to your device, it will have a strong signal (all or most of the bars will be filled). 

Screenshot 2021-02-22 at 13.13.52

Note: Once you click ‘Pair’, the block should immediately turn blue.