Caution, remember before you connect the ST to your scale, put the scale power cord in its box, you must power the scale via the ST and its power cord.
I used my scale first, then added my ST later. I found it far easier to reset the scale to factory settings, then configure as per the instructions in the ST manual.
Using the v3.0.5 manual:
I'd start by reviewing pages 13-16 but don't actually do that. At this point your have the ST plugged to the scale and both are powered on or in standby.
factory reset starting page 17, then continue to configure it below that, if you mess up and get lost, simply factory reset it and start over. You're doing all this on the scale as per the instructions, ignore the ST until all done.
It's important that you get page 19 step 21=gn and 23=g correct as that sets grains as the primary and grams as secondary, no others should be configured. It obviously need grains for powder, but your check weight is in grams and why that's needed and the order matters. After 26, if you're using a 100g check weight, ignore the next section as that's for if your check weight is 50grams.
Next walk through all the sections and check each setting as indicated starting pg 20. If your scale has some other than expected firmware this is where you would find something set other than desired. By now you likely have a good handle on how to move around the scale menu and change settings, if you find something wrong, correct it and save the setting. Also since that would indicate a one-off change, make a note for future reference ;-)
Continue with pg's 22-24 checking communication with the ST and then the calibration steps.
If you've been through above and the ST still shows different amounts on the screen than what the scale shows, power off via the ST menu, verify the scale is NOT in standby mode (no lights), wait at least 30 seconds and power on via the ST screen. Check again and if they don't register the same, then walk through the check settings starting pg20. I'll bet you'll find one is not correct, maybe for whatever reason something wasn't saved.
You can of course check the FW version on the scale against what is expected and if other than what the ST expects, maybe contact support for your scale and see about a fw update for it, although that may require shipping to them if it's not user upgrade-able or you're not comfortable doing it. I just noticed you said your scale is new, so maybe it's got a newer FW than expected, not older. Easy enough to check the version.
Since you got the ST from another person, if you're still having issues, if you're sure everything is correct you might do a full factory reset on your ST. This doesn't change scale settings, but any configs in the ST will be lost as the full factory reset does just that, a clean start. I actually have found on my unit I must do this before updating ST firmware otherwise I get weirdness after. In my case I first back up all my configs, then put the sdcard back into the ST and do the full reset. Then copy in the new fw and put my files back and run the update when prompted on insertion. I've updated since getting it new with v2.10, I updated and started with v2.40 and many updates since. I'm currently running v3.0.4 but that's only because I haven't go around to updating to .5
Hope this helps... I know for me it took a few times through the scale menu when I got it to get the hang of how to move around and actually change/save settings correctly. Then once I got the ST I had to kinda relearn that again as it was months later. I found it immensely helpful to print those pages, 17-22 in the v3.0.5 manual and have them right there next to the scale.
