There is no "fix" for hearing encrypted tranmissions.
According to the RadioReference database, 4 of the Sheriffs talkgroups, the Beach L-E dispatch talkgroup, and all 15 county interop talkgroups are encrypted.
If you're still hearing the dispatch side of some of the encrypted talkgroups, you're lucky ... dispatch may be operating in the clear as a courtesy to other agencies who monitor Dare County communications.
No scanner, including the 996xt, can receive and decypher encrypted P-25 voice comms.