qmenubar hides when resoultion of the monitor changes

[wagmare]

hi friends,
i am facing a strange problem with qmenubar. i am developing the mainwindow with a resolution of 13608768 . i created a menubar and altered with some stylesheet

QMenuBar { padding-left:-4px; spacing: 8px; background-color: qlineargradient(s);
border-bottom-width: 1px;
border-bottom-color: rgb(26,131,212);}
QMenuBar::item {
padding: 1px 4px;background: transparent; border-radius: 0px;
}
QMenuBar::item:selected {
background: z);
color:rgb(255,255,255);}
QAction {spacing: 3px;}"

and from my screen resolution the qmenubar is coming perfect as 10012
but when i tested the ui with bigger monitor
the qmenubar is coming like all the menuitem are formed as a drop down list at the right corner of the menubar
like this 10013

please hep me in solving the problem .