Hi @uros.simic
First off, welcome to the Cayenne community, my apologies that it is under the circumstances of this bad experience. As you’ve seen, the broken Save button is a bug that’s limited to this one sensor type via the web dashboard. We’ve detailed it in this thread: Problems with DS18B20 widget with Firefox/Chrome as well as some others you can find if you search DS18B20.
The suggestion from picaxe is a good one for the short term, if you have an iOS or Android smartphone you should be able to get this particular sensor added and configured from that interface until we fix the web widget.
Regardless, I’ll update this thread, and related ones, as soon as we have a fix.