I’m having trouble saving files with a pdf reader and have been advised to add the program to the list of trusted applications in Avast.
The problem is I cannot find how to do that. Avast does not mention that the program is untrustworthy, but it may be preventing it from writing a file.
Please explain how to add the program to the list of trusted apps. I am using Avast Premier. It says I have the latest version.

What reader are you using ?
A reader is just that, it reads and doesn’t save files.

What message is avast showing you ?
What is mentioned about in the avast log file(s)?

I’m using Tracker software PDF Xchange reader, which has a (limited) capability of saving opened files. But now somehow when I try to do that, i.e. save a file with added annotations, for example, something just closes the reader. How do I open the avast log? I get no message - it’s been suggested that the behavior I’m seeing might be caused by my antivirus software, so I’m trying to look into it. I’ve found an Avast log file, but I cannot open it. The monthly report says everything is safe.

maybe pdf xchange reader is corrupted.(Reinstall? contact support?)
install adobe reader instead XD. I have no problems with it.

Is everything fine if you don’t change the pdf and save it ?

I do not think the reader is corrupted. I have redownloaded and reinstalled it, not once but several times. This does not help.
Also, when I try to save the unchanged pdf document, the same thing happens.
I have reasons why I do not want to install Adobe reader - this suggestion was not helpful. I have also reached out to the software producer. They have no answer for me except to add the executable to the list of trusted programs. So can anyone answer that question for me?
I’m using Avast Premier.

What does it mean if I cannot open or save a file when running the application in the Sandbox? This gives me a message that the app has reached a user-defined breakpoint. Since I have never before used the Sandbox, I have no idea what this could mean. Help please!

If you run something in the Sandbox everything will stay in the Sandbox and will be gone when you exit the Sandbox.