Unanswered Topics - Notebook

Hello everyone! I am new to this community. Recently I have bought my first ever laptop, and it is a HP 250 g6 3VJ17EA. I bought it in a shop, it is not pre-owned or anything. And even being new, I have noticed a few problems with the battery, so I thought to ask in this community for help. As I previously said the laptop is brand new, took it out of the box myself. After reading the instructions(where it said that I must plug in the ac adapter before using the laptop for the first time) I plugged in the ac adapter, turned on the laptop and saw that the battery was 99%. A little later the battery was draining, even though the ac adapter was plugged in. After some quick searches online I found out the location was turned on. I turned it off and the battery was working normally(staying 100% when the adapter was plugged in, and draining when the adapter was unplugged). A couple of days ago I noticed another issue with the battery. When the adapter was plugged in the battery would show 100%, but as soon as I would unplug the adapter, the battery would show 95% in a blink of the eye. What should I do to fix this? Because if the battery has this problems now that it's new, I don't know what issues will have after a few months of use.
And another question.
How many hours should a laptop's battery last? Being a new battery and all... Somewhere I read they should last 4-5 hours, elsewhere 2-3. According to the specs of the laptop I have bought, the battery is Lithium-Ion, 3 cells and with a 31 Wh capacity.
I don't play games on this laptop, just use it for facebook, youtube, and sometimes watch movies.

Waiting for responses. Thank you in advance