Hello, perhaps you can help me. I don't know what I have to change. If I try to open a calc file after transfer to my phone, I can only open the file for reading only, but if I open a new file, then there is no problem.
Most likely the file you're trying to open is read-only. It's in this mode because it's possible you've created it in some other software. There is a very simple fix to this problem. Open the file on Android, then use the Select All function. Create another file of the same type, while having the data copied to clipboard and paste it. Save the new file and it should be editable and accessible every time you want to add or delete something. The office package you're using might not recognize files created with other apps even if you can open them.