Having trouble with doors in chrono trigger

[helloimnew]

im supposed to press L+R and A to unlock a door but i am using a keyboard and i cant do that. please help.

i read in a different thread that you can reassign keys but i couldnt find out how.

[Ryu]

i read in a different thread that you can reassign keys but i couldnt find out how.
In the controls setup set two or more buttons to a single key on your keyboard that way you don't have to press more than three keys at once.

[GameGeeks]

Locking due to multiple askings of the same question. And don't double post, tc.