The message relating to accounting policies is a warning message (which can be skipped) informs you that some of the accounting policies have not been selected and even the nominal codes relating to the same is used.

In case if you want to disclose the details for the same, you may select the relevant accounting policies under Settings>>Report Settings>>Accounting Policies. 

Once done, please regenerate the accounts report to see the impact.

Please refer below screenshot for more help.