First, I have added the screenshot (sorry, but I do this so often that I sometimes forget).
Second, the issue of reduction (in the limit, I assume you meant) is a question of HDHP coverage, not HSA. The HSA belongs to you, not your employer, and you can keep it if you change jobs. You just have to tell the new employer to send the contributions to the old HSA.
If you have already created a second HSA and there is money in both, you can decide which one you want to keep and call the HSA administrator to ask them to roll it over to the other account.
If you didn't do item #2 above (the usual cause), then make sure you indicated that you had HDHP coverage for every month that you did (and that you didn't have Medicare and that you didn't have a carryover from last year, and so on).
