OK Richard. I’ve been using my Winradio SDR recently and have left my RSP2 disconnected for a while. I’ve just plugged it back in and downloaded Uno 1.33 to make sure I’m up to date.
All the buttons you need are in the small MAIN RX CONTROL panel, the one with the RF gain slider.
First of all, change the mode to ZIF (zero IF). This will give you access to the Sample Rate (SR) and Decimation boxes. You should see these roughly central in the panel. The lowest SR is 2 MHz, so if you want a smaller span you should click in the Decimation box to bring up a division number. Choose a number that gives you something close to the span you want.
Note you cannot do this if you are using the ‘band’ buttons, as this fixes the SR and DEC selections.
If you select LIF (Low IF) you cannot choose the SR, only the DEC.
Hope this helps.