There are different ways to select layers in Photoshop.
1. Click on the Layer and then hold the Ctrl key then click on the 2nd layer, select as many layers as you want.
2. Other method to select all Layers is that create a folder and start creating layers in the folder with that you will select all layers with just a single click by selecting the folder.
3. Third way to select all layers in photoshop is that select the first layer then hold the Shift key and then select the last layer in photoshop, by doing this all layers between first and last layers will be selected.
I hope by reading this blog post your issue has been addressed.
For How to Select Multiple Layers In Procreate click on the link