♦ I store my finacial documents in a fire proof safe. (documents)
♦ Its a good idea to have extra copys of financial information incase your origanal is damaged. (copys)
♦ To store financial information properly I need to organize all of the bank statements. (statements)
Am I using plurls correctly in these sentences?
Yes, but in the USA the spelling for #2 is copies, not copys.
I would also question the wisdom of the second statement, depending upon the type of the financial documents. You will be drowning in copies eventually if you try to keep copies of all bank and brokerage statements, and real estate cost basis documents, for example.
Yes, you are using plurals correctly in these sentences.
The word "documents" is plural, which is appropriate since you are referring to multiple financial documents stored in a fireproof safe.
Similarly, "copies" is the plural form of "copy," and it correctly conveys the idea that having multiple copies of financial information is a good practice.
Lastly, "statements" is also the plural form of "statement", and in this case, it correctly indicates that you need to organize multiple bank statements for proper storage of financial information.