Thank you all for your reply.
@ranochigo : When I send bitcoins to anyone, I don't mess with the fees.
Could you guide me how to set the fees correctly so that when I send bitcoins, it will "always" be in High priority ?
Thank you all again.
By default, Bitcoin Core 0.10+uses a mechanism which estimates the fees needed for x blocks before confirmation and it assumes that you don't need the funds immediately hence they would introduce a slower fee. They
To adjust the fees, go to Send tab,
and you should see this:
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FdXAiPB8.png&t=663&c=n_oTv-VAiVPttQ)
Click the the choose... beside the transaction fees to choose the specific transaction fee.
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FWmWPmUQ.png&t=663&c=uuzfLuQhlQHxuQ)
You can adjust the slider based on how much block you want it to confirm. It isn't fully accurate however due to the fact that miners can reject your transaction.