Hi， Thank you for your reply. I have found the line but the default value is true already.
It is a weird phenomenon even for almost blank document. Dear all, I have set the sumatra as my defalt PDF viewer of LyX. But there will a new PDF each time if I compile it using CTRL+R. I want the output to overwrite the old PDF. Is there anything I can do? As per the Sumatra PDF documentation ;-) — in "Settings" select "Advanced settings" to bring up the advanced settings file in your default text editor. Find the line for "ReloadModifiedDocuments" and edit it to read: ReloadModifiedDocuments = true Note that I believe there is a size limit (10MB?) after which Sumatra will not do auto-reloads even if you set this parameter to "true". -cm
