I made a friend warlock and on the app all the spells I learn keep getting put in the level 3 slot regardless of what level they are. If I view the character as a pdf the spells are all in the correct place so I know this is not intended. I can manage by printing the pdf obviously but I like using the app so would like it to work properly. For clarification I am saying that in the spells section all my learned spells are automatically only castable as level 3 spells and consume a level 3 slot.

That is the way a warlocks spell casting works. You get less spell slots than other casters but they are all at the same level as the most powerful spells as other full casters, you also get the slots back after a short rest.

As a level 5 or 6 warlock Whatever you cast a spell other than a cantrip it is cast using a 3rd level slot , therefore when selecting spells you want to pick spells that upcast well, or at least plan to swap them out when you level up.

When you reach level 7 your spell slots will become 4th level.

Oh okay thanks. How come they are in different slots online?

The spells are of different levels, but the spell slots are all the same level.