my apps continually go back to the home page

Hello.

I have a problem with my iphone once I have more than one app open at the same time. Every time I have an app opened, if i double click on the phone’s central button to view all my currently open apps and then go back to the first app, the first app goes back to the homepage, no matter what I was doing or writing. It’s like it automatically restarts.

Ex: I’m on twitter writing a tweet. If I double click the central button, select any other opened app to check something BEFORE sending the tweet on the twitter app, and then go back to twitter (without closing the twitter app but just by checking another app for few seconds), you can be sure than 99/100 of the times it will go back to the “tlist”, the homepage of Twitter where you can read the people you’re following tweets, and consequently delete what I was writing. It doesn’t happen with Twitter only, but with every other app (like FB, translators, Safari, Whatsapp, ecc).

What can I do? does it happen to you as well?