You control whether a line says new or old.
For instance you can use "select all" and the right click menu to mark everything "old."
If later somethings shows up as "new", it probably is.
I think the date may be the oldest date in certain of the application's registry keys. It is probably a "best guess" at the installation date.
This quote is from the PT Handbook:
"Please note that the Software Manager works based on approximations, this means the list can contain some number of errors, for example the software's Main Executable information or the Installation Date might not show the correct data on all software. This is normal. Also, it's not always possible for the Software Manager to detect e.g. The Installation Path of the software, in such case an “N/A” is shown.
Because of this, the Uninstall button doesn't use the extracted information (such as the Installation Path) without asking a permission from you. If you wish to remove all traces of the software you must use the Custom Uninstall feature. "
Carefully read the Software Manager section of the Handbook. It is probably safe to remove registry entries for a no longer installed application, but a human brain has to make the actual decision.
If one does not know for sure, one can chose "never show again" by selecting one or more lines on the list and using the right click menu.
About safety -- always specify back up when removing or changing anything. You can restore if something goes wrong. Except for uninstalls -- the recovery for that is to reinstall the application!
