However, devs of bitcoin-qt are against SegWit2x, and I use the bitcoin-qt program to access my wallet in my computer.
Should I change the program in case the support reaches 95% as indicated in the site above? I have got the private keys using console commands in bitcoin-qt, so this would not be a problem. But if I send throughout bitcoin-qt will my bitcoins be safe after miners reach 95% consensus and the devs keep going against it? And what program I could use in place of bitcoin-qt, in case this might happen?
As long as you have your private keys, your Bitcoins will be safe. You should be able to find a wallet you can import them in, if need be. In fact, if the chain splits, the coins you have at this moment will be on both chains. You will need to be careful about moving any bitcoins after the chain splits. I'm sure there will be plenty of solutions available within the month that will allow you to enjoy the coins on both chains and move them safely.