Homing failure motors jam

So im new to this whole 3D printing thing and started to build my own printer which is a mendel type one to be exact a franzis mendel which i build according to a book i bought.
The printer is now completed atleast on the hardware side but i now started to install Marlin (im using the RAMPS 1.4 board with an Arduino Mega 2560 and A4998 stepper drivers) and as a control software for my pc im using repetier.
I at first tried to move the axes over the manual controll tab and adjusted the potentiometers so that every motor is moving its axis. X and Y are moving fine but the Z axis motors do after moving them produce some slight high frequency sounds. But the real problems are showing when i start to press the homing buttons on the manual control tab the X and Y motors start to sound like they´re jamming but only for like one sec and after that they start to move. But the Z axis motors dont stop with their jamming sounds they wont move ( I immediatly pressed the reset button on the board or atleast as fast as i could). At some point pressing the X axis homing button even moved the Y axis but this happened only once and I didn´t manage to replicate this behaviour. The printer was just set up and i have never printed anything with it its the first attempt to calibrate it. Tried to get it done using the books tips but i tried everything and it didnt work out neither have i found something on the forum or somewhere else to this specific problem so at this point I´m hoping to find help here.
I uploaded some clips to youtube where i at first move the axes with the manual control and then try the homing buttons i hope this helps.
Motors manually controlled
Homing jamming
If you need some further information or more visuals dont hesitate to ask.
Thanks in advance from a newbie.

For the Z axis - if you are using 5mm threaded rod then your DEFAULT_MAX_FEEDRATE is properly too high

The default is 5, change it to 2

#define DEFAULT_MAX_FEEDRATE {500, 500, 2, 25} // (mm/sec)

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My updated Instructable on our Prusa i3 Build
[www.instructables.com]

Wow thanks this seems to have helped at the Z axis eventhough I´m using a 6mm threaded rod thanks they´re not even making that high frequency noise at the start but the X and Y axis still do their jamming sound before they move is there a line which i also need to change here like for the Z axis before ? And do i understand this correctly the feedrate is basically the velocity of the axis movement ? i now changed only the 5 to an 2 but the line on mine also has those 300 in it do they change something else?

#define DEFAULT_MAX_FEEDRATE          { 300, 300, 2, 25 }

4 numbers are for the X Y Z E motor speeds, the 300 300 and 25 should be ok, it is just the Zdefault Z speed set in marlin that is too fast for 4000 steps

This may be helpful, see my post, 5th post from the starting post:
[reprap.org]

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

Ok so i think after finally playing with these feedrate numbers which i had to readjust after setting the correct speed for the steppermotors this seems to have helped thanks to guys