I set the session time of any user to 1 hour before they automatically log out of the account. I just checked, everything works for me as before....

The solution for you if you keep getting kicked out is to clear the cookies files on your browser.

Examples In Chrome
1. On your computer, open Chrome.
2. At the top right, click More .
3. Click More tools. Clear browsing data.
4. At the top, choose a time range. To delete everything, select All time.
5. Next to "Cookies and other site data" and "Cached images and files," check the boxes.
6. Click Clear data.

After that, go to your Absolute Forum account and check if you are still log out after couple of minutes.