PDF files are only created and opened as read only, only

I work with Adobe acrobat Pro XI

I do not know when it started, but I cannot store  files under the same name anymore  after editing it.

Even if created it new myself once stored and opened a second time, if I want to store it it say I have to use another name because the file was opened read only, or I am not the owner.

Also when I change read only un der "propeerties" I cannot store it a second time under the same name.

Adobe suddenly opens and creates only in a read only setting.

I do not have a clue where to start looking, but it is a seriuos problem each time use another name, then delete the old one and than rename the new revision in the old name.

Where can I change the setting  to open and store in read and write again?