Pass gs.daysAgo into a new GlideDateTime record and then obtain the display value of that new record.
\r\nFor example, instead of using:
\r\njavascript:gs.daysAgo(-5);
\r\nas a default value, use the following:
\r\njavascript: new GlideDateTime(gs.daysAgo(-5)).getDisplayValue();
\r\n