Restarting the NAS actually did it for me, but if that doesn't work...
Found here --> https://community.synology.com/enu/foru ... ort=oldest
I finally managed to sort this out using advice patched together from different sources. A few people have asked for a step-by-step, so I'm going to try and do that here.
The problem: torrents sitting in a "waiting" state after I disabled the admin account (as advised on new DSM)
The issue: without getting too technical, all the waiting torrents had the user listed as "admin", rather than my more recent downloads, which have a newer username (the one I use to log in). Others above have suggested logging in as the other account and changing the default download location, but that didn't work for me, as I still wanted to disable the "admin" account later.
The need: change all the 'waiting' torrents' username from admin to my desired new one.
If this sounds like you, please read on:
You need to first go into DSM on Control Panel > Terminal and SNMP and enable SSH. It's good practice to disable this afterwards to reduce the possibility of getting hacked.
Go to Putty or just a standard Command Prompt on Windows or Terminal on MAC/Linux. All of this I did through terminal on a Mac
type in: ssh USERNAME@YOUR.NAS.IP (this also works if you use a dynDNS or similar). Replace USERNAME and your NAS IP, if that wasn't obvious. It's unlikely, but if you get a connection refused, it's likely port 22 is being blocked on your router, so you'll need to do a port forward on your router if so.
Your password will be the one you use to log into USERNAME on your NAS DSM
1) Type: sudo -i (Enter same password)
2) Type: su - postgres
3) Type: psql -l
4) Type: psql -t -A -d download -c "UPDATE Download_queue SET username='DESIREDUSERNAMECASESENSITIVE" (replacing the desired username with your own)
5) exit terminal, and disable SSH as described above for security.
If it's worked, you will get a number which equates to the number of torrents that have been changed to the correct username. You can now disable the default admin account. You can check in Download Station that all the torrents do have the desired username. Worked a treat for me.
4) Type: psql -t -A -d download -c "UPDATE Download_queue SET username='DESIREDUSERNAMECASESENSITIVE'" (replacing the desired username with your own)
Download Station Waiting
Download Station Waiting
You Wouldn't Believe How Hard I Have to Work to be Lazy