To start connecting with other devices, you need to set your Bluetooth status from invisible to visible.To set Bluetooth visible on HTC One and set timeout do as follows:
1. Open "Settings"
2. Enable "Bluetooth" and tap it to enter Bluetooth setting
3. Tap your Bluetooth name to set it visible (by default the name is HTC One. To change it, see: How to Change Bluetooth Name on HTC One
4. Tap again to change the status to invisible
5. To change the visibility timeout, tap the three dot icon on the top right, and select "Visibility Timeout"