TXID and Output Index

To verify that your TXID and Output Index are correct, open the debug console of your wallet and type the command:

masternode outputs

The list of valid TXIDs for masternodes will be shown. The first column is the TXID and the second column is the Output Index.

To change on ZCore Central, go to the dashboard https://central.zcore.cash/mn-dashboard and click on your masternode.
On the details screen, click the TXID and the Output Index to change according to the one shown in your wallet.

After that, click the masternode.conf [SHOW] button to copy the correct configuration line for your masternode.

If your TXID does not appear in the list your masternode will not start, in which case you should create a new TXID:

https://medium.com/zcore/recreating-txid-7d033f942052