First of all, before installing, you have to decide which of the cards you want to install the application on. There is a memory card that is already built into the device and cannot be removed, and there is an external memory card on which you can install the application you are interested in. In this case, the "native" memory card is also called as a ROM.
By default, all applications are installed on the "native" memory card of the phone and if you want to install the application there, then you just need to perform a standard installation of the application. At the same time, if the application cannot be installed there due to the fact that there is not enough free space, then you will have to delete unnecessary applications and programs that you do not need.
Installing apps on a third-party phone memory card with Android OS can be quite difficult if you don't know how much free space is left on the phone's memory card. In order to see how much free space you have left on the memory card, you can use any third-party file manager, or you can remove the memory card from the device, insert it into the card reader and see how much space is left on it. If there is little or no free space at all, then you need to delete those files that you will not use. If there is enough free space, then you can remove the memory card from the card reader and install it into the device.
Similar manipulations to clean up space on the memory card can be done in the phone.
After you have made sure that you have free space, you need to go to the "Settings" menu item, then select "Applications", and then select "Transfer" near the application you need. After you have done these steps, you can transfer the application you need to the memory card. Remember that one way or another the application must be installed on the phone beforehand.
If the "Transfer" button is inactive near the desired application, then this means that the application developers have not provided for the possibility of transferring the application to an external memory card. Do not worry, this sometimes happens and it is impossible to get around by conventional methods. Just have to do nothing with it.
Also remember that the transfer function is only available in Android with version 2.2, no less. If you have an earlier version of the operating system, then in this case you will not be able to do the above operations to transfer the application to an external memory card.