Dear yardy and WeatherCat faithful,
Hi, First time posting so please be patient.
Since this is your first posting, let me welcome you to the WeatherCat forum!

Upgraded to Big Sur and installed the USB driver - all went well. However I find that the horizontal resolution of my custom graphs has changed. I collect data every 15 minutes and that is what used to be displayed. Now under Big Sur the horizontal resolution displayed is 30 minutes and I cannot find anywhere to control this. The Standard graphs all seem to have 15 minute resolution. Any suggestions on where to check or what to change ?
I cannot imagine anything other than perhaps your sampling interval was changed when you upgraded to Big Sur. The sampling interval is set on the Misc2 pane of the WeatherCat preferences. The screen is shown on page 164 of the WeatherCat manual and the description is on page 171 of the manual. It is a long-shot, but perhaps it isn't where you set it before.
Let us know what you discover.
Cheers, Edouard