As we have now payout threshold some of the coins are held and not paid. My question is the next: if i my node was not paid this month and still have accumulated coins, what will happen if i change a wallet address? Will i loose accumulated coins (as they where earned with other wallet address) or this does not affect and next month (if i reach the threshold) i will receive all amount ?
If you change the wallet address then all outstanding payouts, due for that node, will be paid to the new wallet address (assuming you reach the threshold).
Once you changed the configured wallet address and restarted the node, simply double check the change was taken into account on the web dashboard to be sure