Forgot to allow reconciliation for an Account in Odoo and now getting "You cannot change the value of the reconciliation on this account as it already has some moves"? This short tutorial will guide you on how to Allow Reconciliation at any time. Please note that some skills are needed.
Backup your Odoo, download and prepare your server for connection to the Database.
Use my tutorial on how to connect to Odoo using pgAdmin if necessary.

Find the account you want to Allow the Reconciliation and change the field "reconcile" to true.
Save the changes and restart the server. Remember not to do any changes in the DB in the Live DB. If you have to do so please test it first and apply the changes outside of the working hours.
Check the results
Refresh the page to check the results.

References
Read more on the official Odoo Help forum:
How to set "allow reconciliation" for existing Accounts in Accounting App
In case of any questions feel free to contact me.
Allow Reconciliation for Accounts in Odoo
How to solve "You cannot change the value of the reconciliation on this account as it already has some moves"?
Odoo Odoo Accounting