Your knowledge about blockchain is very useful for new people in this technology!

Now I can understand the whole process of making a token and distributing it to the people, making blocks and having the wole network secured. But still there is a one doubt:

We all know that blockchain has plenty of reasons why we should adopt this technology. One of them is security and authorisation of the transactions which makes is safe, secured and authorised. In addition to that whole data inside blockchain can be kept there for ages.

So here is my question : If I would use the blockchain technology in my company for example in money transfers, then I will be the only one person who gave the public keys to other people, (and who created whole project) then how others can proof that I just changed some information inside a blockchain?