Forks for any cryptocurrency are pretty simple so long as you keep one thing in mind:
Control your private keys.
If you do not control your private keys, your MSR is not your own, nor would your BTC or XMR be your own. Stocks.Exchange has not been responsive to Thaer in letting him know whether their infrastructure is aware of or supporting of the fork. So if you were to successfully withdraw MSR from Stocks.Exchange around the time of the fork there is a chance you will lose your MSR, since it might be old-chain MSR from before the fork, which would be rejected by nodes. The only way you could spend that is if there were a Masari-Classic for example.
So, in summary, as long as you control the private keys you have nothing to worry about. Your cryptocurrency has nothing to do with a PC, a hard drive, a file on your hard drive, or a software wallet; only to do with your private keys. You should keep these backed up in a safe way physically or digitally, I personally encrypt my seeds in plaintext within a 7zip archive via aes-256 and then split that archive into 3 pieces, which I then keep backed up on a self-hosted cloud service. However, writing your 25 word mnemonic seed down on a piece of paper and keeping that safe will also suffice.