Exchange rate

We have tried to change the exchange rate for a new period by creating a new exchange rate in a specific date, but the previous periods got effected too we are using the version number 19.7.7 server edition, also can i know whats the latest changes in the new version.

Your version is many hundreds of updates behind. You might barely be within the one-year period for free updates. I would check immediately.

So if i update my version to the latest this would be solved?

I did not say that. You have not furnished enough information to tell. But the Guides and answers in the forum are from the perspective of more current versions of the program.