通常我们在app.json中统一设置title

 "window": {
    "backgroundTextStyle": "light",
    "navigationBarBackgroundColor": "#FFFFFF",
    "navigationBarTitleText": "心灵密友",
    "navigationBarTextStyle": "black"
  },

在单独页面要修改的话可以在，对应页面的json中修改

"backgroundTextStyle": "light",
"navigationBarBackgroundColor": "#FFFFFF",
"navigationBarTitleText": "单独页面",
"navigationBarTextStyle": "black"

也可在js中动态加载

onLoad: function (options) {
    wx.setNavigationBarTitle({
      title: '当前页面'  //修改title
    })
},