Hey @juliaasatryan, here's the difference between black and grey post titles.

Black means you haven't clicked and viewed the post yet.

For example,

This means I haven't clicked and viewed the post yet.

Grey means you've clicked and viewed the post already.

For example,

This means I've clicked and viewed the post already.

The value of your post changing is a bit complicated.
There's 2 reasons:

1. There's a fixed amount of the reward pool that all of Steemit has access to. If more people takes from the reward pool, then the percentage of our personally allocated amount goes down. Hence, the your post value going down.

• If more people are active, post payout goes down.

1. The value of the Steem currency is not fixed. So, if the price of Steem on the market goes down, then, the value of Steem on your post will drop as well.

• If the value of Steem on the market goes up, then your post payout goes up.

So, NO, you did nothing wrong.

Are you on discord? If so, then I can guide you and share some tips about Steemit. Add me @Scuzzy#7843 .