Поменяйте текст выбора с JavaScript
var sel1 = $("#se1");
var sel2 = $("#se2");
function swap() {
let selection1 = sel1[0].selectedIndex; // Store the first list's selection
sel1[0].selectedIndex = sel2[0].selectedIndex;
sel2[0].selectedIndex = selection1;
// Test
console.log(sel1.val(), sel2.val());
}
SAMER SAEID