Upvote:6
Based on your description it sounds like you have had a criminal conviction of some type in the past. The fact your previous visa took many months to be approved sounds like the process that occurs when you are found ineligible for a visa, but you apply for a "waiver of ineligibility" which was subsequently approved.
In cases like this, it is not uncommon for them to issue a short-term visa - in your case only 1 year rather than the up to 10 years they can be issued for. The length of the visa is entirely at the discretion of the staff issuing it - there is nothing specific you can do to request a longer visa.
However if you apply for a new visa - and if your situation has not changed since the previous application (ie, you haven't committed any crimes since then, you didn't overstay on your previous US visa, etc) then it is likely that you will be issued with a longer visa. There is no guarantee that this will be the case - it's entirely up to the consulate staff's discretion, and whether they believe issuing you a longer visa is a risk or not.
Presuming you did require a Waiver of Ineligibility for your previous application it is possible you will also need to apply for one on this occasion (it depends on what was previously approved), so keep in mind that the entire process could take several months once again.