setting tempo

[sugarplumsss]

i've been suspicious of the + - buttons for tempo
i played a t5 and it confirmed my negative opinion about my particular t4

other than the obvious - press + to increase tempo. - to decrease
what other button pushes are part of the design of the two buttons ?
i've seen - while moving the tempo between songs - tempos jump backwards by 10 bpm
i know press both buttons simultaneously creates the default tempo immediately
but i've seen a number of frustrating tempo changes ( as i'm pushing buttons ) that at first i assumed
must be intentionally designed. to eg jump forward or backward

my recent more positive experience with T5  causes me to ask
please provide ALL button push options that are designed into the two
buttons

1) push both. = default tempo
2) please name any others

thank you

[jwyvern]

1. Push + and -  simultaneously = default termpo
2. Push either momentarily = raise or lower tempo by 1
3. Push and hold either = raise or lower tempo continuously. Be careful not to linger on the button and cause this inadvertently if you don't want to see jumps.
John