Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to use bluetooth headphones on pc or mac [title] Charge or insert fresh batteries in the headphones. [step] Before pairing any bluetooth device, make sure the device has plenty of battery power. [title] Put the headphones in pairing mode.

Ending1: [step] Make sure they are firmly on (or if they aren't, let them stay off. ) [title] Insert the ipod into both headphones. Ending2: [step] Insert the headphones into pairing mode using bluetooth features (none). [substeps] On an iphone or ipad, slide the bluetooth switch to on and tap the " battery " icon (24 red triangle with the two horizontal lines crossing). Ending3: [step] Putting the headphones in pairing mode will vary depending on the make and model of your bluetooth headphones. In most cases, there is usually a button you press and hold to put the headphones into pairing mode. Ending4: [step] If you can't use bluetooth headphones in pairing mode, you'll need to connect the headphones to your pc. [substeps] If battery power is turned off before you insert the headphones, unplugging the earphones can help determine if the device is bluetooth compatible.

Answer format: ending1/ending2/ending3/ending4