I was using this chat service for over 2-3 years now. Recently, I read their privacy policy and it says they can just do anything with data

  • They can collect all chat, files and everything.
  • Can keep it for whatever time they wish.
  • They won't rent, sale this user data but they can give "certain" information to third parties but haven't mentioned what this certain is. They also state that they or their partners can give any information to legal authorities without ever informing us.
  • They also state that they can go through any of our communications and files whenever they want.

Their website have the updated privacy policy from recent month which says they can collect communication data and files. But on mobile they show a old policy on latest app, from 2012 which doesn't say this particular thing about collection of communication data and files. It has to be to deceive customers right? And even if is not intentionally it has to be in the favour of users as they actually accept terms of old policy, right? Then again they have URL to their site and states that they have right to change it with or without informing users.

well ...
that's the story of life, and not just online.

basically, the same applies to laws of a country. they are set, altered, changed, ... by a small group of people, that supposedly "represent" the citizens, but, basically, when these bills and laws are voted, we can only hope that they
1. bothered to show up, hell, they get paid anyway
2. bothered to read up on what it is they're voting about
3. bothered to think about the implications of both passing and not passing it
4. bothered to stay sober
5. bothered to stay awake long enough
6. ...

some of these laws and bills are only meant to earn tons of money for the government, with zero added value for the citizens.
others mean a heap of increase on the politicians' popularity, while they basically just dump every bit of value there is in the education system of the country. "oh, no we won't fail these children. of course, they don't have enough knowledge to actually pass, but they wouldn't like being left for a year, they wouldn't be with their buddies anymore. oh, hell, green passes for everyone" (not a joke, this actually is happening over here)

they change the laws without asking permission to the people, the documentation the people get is hazy at best, but, you had better follow them, because you'll be the one paying if you don't.

for a site, it is to be expected that they change policies now and then.
let's say you have ten rules, but none of them are about posting spam on the page. at that point, some guy starts spamming the page. of course, common sense dictates you shouldn't, but still, it's not an actual rule.
the spamming blanks out more valuable content, and reducing the reason for serious members to stay members.
will you allow the spam, or will you create a new rule, stating spamming is gainst the rules, and will be removed, and might get your membership revoked ?
in my experience, the latter is the better option.

if you have 25 members, you can take a poll on their opinion.
the page on which I am one of the moderators, though, has over 100K users. it's impossible to please everyone, or to go around and ask everyone.

The rules you mention are pretty typical for publishing content on the web. They are not unlike our own terms, which we update as well from time to time to reflect changes in our community. It's not done to deceive anyone. It's done to preserve the integrity of the community through changing times.

It wasn't a website, it was a chat application. Even Daniweb promises to never go through private messages.

I could have understood a 2-3 month difference in privacy policies, but their latest application have privacy policy from 2012 and website have privacy policy from october 2014.

Even Daniweb promises to never go through private messages.

Which seems like a mistake on our part. Daniweb's TOS should probably include a qualifier that PMs may be reviewed in extreme cases (such as excessive harrassment) or shared with law enforcement to assist in any investigation.