Sorry for the delay - big issue with one of my customers. I have a buttload of videos to re-encode, but I've got it sorted and can get back to my own stuff now.
OK, so Session Keeper uses standard Joomla translation files. This means you can use the Extensions > Language(s) > Overrides feature of Joomla to change the text (yay!)
While in the Overrides view, choose "Administrator" from the "Filter" menu on the left and then click the "New" button.
Because there are 2 different display options and they behave slightly different, there are 2 language constants. So you'll need to alter the correct one for your setup.
PLG_SYS_SESSIONKEEPER_WARNINGMESSAGE for the modal notification
Pick one, and paste it into the "Language Constant" field of the form.
In the "Text" field of the form (directly below Language Constant), you'll type the new text you want displayed.
Save it and it's done.
This method of changing the output will survive upgrades and it's a good thing. I'm about to release a new version of Session Keeper that uses the Joomla updater (as well as a few performance enhancements)
I hope everything goes well, and let me know if you need any more info!
That is fine Michael. Thanks for that clear explanation, I should have remembered that! No problems with the delay - it happen to all of us even in retirement! I will check it out - a delay first while I go mix some concrete.