How do I connect JBL earbuds to iPhone or iMac via Bluetooth?

first time you pair a bluetooth device with a new device you need to make sure that

1. the bluetooth device is in pairing/ discovery mode
2. that the bluetooth device do not have an active connection with another device

about jbl pairing mode then AI says

"To put your JBL earbuds into pairing mode, remove them from the charging case, and if they do not connect automatically, tap an earbud once and hold it for 5 seconds until the LED lights flash and you hear a pairing prompt. [1, 2]

Automatic Pairing

• First use: Brand new JBL earbuds enter pairing mode automatically the moment you open the case and take them out. [1]
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• Indicator light: Look for a fast-blinking light (usually blue or white) on the earbuds. [1, 2]

Manual Pairing for a New Device

• Step 1: Turn off Bluetooth on any previously connected phone or tablet to disconnect the earbuds. [1]
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• Step 2: Take the earbuds out of the charging case. [1, 2]
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• Step 3: Tap either the left or right touch control once, then press and hold it for about 5 seconds. [1, 2]
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• Step 4: Wait for the audio prompt saying "Pairing" and watch for the LED lights to start flashing quickly. [1]
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• Step 5: Open the Bluetooth Settings on your phone, tablet, or computer, then select your JBL model from the list of available devices. [1, 2]

"

a youtube video about pairing some jbl headset

JBL Vibe Beam Earbuds – How To Pair - YouTube

more hits

jbl earbuds pairing mode - Google-