Well it looks like success at last, I see you're decoding ok. You might want to drop the audio down a bit, I see the volume light in one of your screen shots is red - they should all be green.
It's just a matter of experimenting a bit, tweaking the frequency to give you the least errors and finding which channels give you the most interesting information - 3 or 4 channels carry USAF Military aircraft - C17's, C5's and KC135's and a few others - just depends where your interest lies
There are around 10 to 12 600/1200bps channels on Alphasat all similar signal strengths (see the screen shot I posted a couple of days ago) but not all the channels carry useful data (just monitor each for 30 minutes or so and see what, if anything, comes in).
If you go to around 1546.000 to 1546.200 MHz you should see six 10500bps channels theses carry the most information and you should see the data coming in quite fast. - set the bandwidth to 15 or 20KHz for these.