What should I do if my ear pain after wearing earbuds for a long time?

What should I do if others can't hear me or my voice is low over a call when I only wear one earbud?

My earbuds cannot work or pair, how can I do?

What should I do if the power of the two earbuds is different?

What should I do if my device cannot charge or charge slowly?

What should I do if others can't hear me speaking over a call?