Can no longer add text to pdf with adobe acrobat dc - windows 10 desktop 64 bit professional

Hello and thank you for your reply! 

This doesn't happen with all documents. I do realize that there are documents that the creators or authors assign specific "permissions" that will not allow certain fields to be added/modified or text to be added. Those are not the documents i am referring to. 

The forms I am referring to are PDF's that I have had and used in the past. Now, these pdf's will not allow any text at all where text is supposed to be inserted. I had always used these forms/real estate contracts, forms from Ohio Div of Real Estate, etc. Now, i cannot interact with any of those forms. Cannot even put a single letter of text on those forms. 

When i attempt to insert a text onto any of these pdf's it isn't possible. 

Do i have to go into the "tools' every time now and if so, when did this happen?

I had my desktop upgraded to Windows 10 and after that i had thsi problme. others I know that have upgraded to windows 10 are having the same problem. The documents are not all from one specific place either. These are random and mostly ones that used to work without any problem and no fees! 

Thank you in advance!