The Insert Button may appear when you insert rows, columns or cells and the formatting between the insert point is different. When the formatting is the same between the insert point, the Insert Button may not appear. After clicking Insert, click the formatting brush shown below:
By default, the button will appear, but please follow the steps below if you need to hide it:
Step 1: Click the "File" Tab from the ribbon;
Step 2: Click "Options" from the left navigation menu;
Step 3: Click "Advanced" from the left navigation menu in the dialog box;
Step 4: Uncheck "Show Insert Options buttons" under the section of "Cut, copy, and paste";
Step 5: Click "OK" at the bottom.