this is my /boot/grub/menu.lst:

timeout 5
color cyan/blue white/blue
foreground ffffff
background 0639a1

gfxmenu /boot/grub/message

title antiX at sda1, kernel 3.7.10-antix.3-486-smp
root (hd0,0)
kernel /boot/vmlinuz-3.7.10-antix.3-486-smp root=/dev/sda1 quiet
initrd /boot/initrd.img-3.7.10-antix.3-486-smp
boot

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

## DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specific kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
## kopt_2_6_8=root=/dev/hdc1 ro
## kopt_2_6_8_2_686=root=/dev/hdc2 ro
# kopt=root=UUID=b190a7bf-2813-42af-a303-564552a8407c ro
# kopt_2_6=root=UUID=b190a7bf-2813-42af-a303-564552a8407c ro nosplash quiet

## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0,0)

## should update-grub create alternative automagic boot options
## e.g. alternative=true
## alternative=false
# alternative=true

## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
## lockalternative=false
# lockalternative=false

## additional options to use with the default boot option, but not with the
## alternatives
## e.g. defoptions=vga=791 resume=/dev/hda5
# defoptions=

## should update-grub lock old automagic boot options
## e.g. lockold=false
## lockold=true
# lockold=false

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0

## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
## altoptions=(single-user) single
# altoptions=(init-3) 3

## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
## howmany=7
# howmany=all

## should update-grub create memtest86 boot option
## e.g. memtest86=true
## memtest86=false
# memtest86=true

## should update-grub adjust the value of the default booted system
## can be true or false
# updatedefaultentry=false

## should update-grub add savedefault to the default options
## can be true or false
# savedefault=false

## ## End Default Options ##

title Debian GNU/Linux, kernel 3.9.5-antix.1-486-smp
root (hd0,0)
kernel /boot/vmlinuz-3.9.5-antix.1-486-smp root=UUID=b190a7bf-2813-42af-a303-564552a8407c ro
initrd /boot/initrd.img-3.9.5-antix.1-486-smp

title Debian GNU/Linux, kernel 3.9.5-antix.1-486-smp (init-3)
root (hd0,0)
kernel /boot/vmlinuz-3.9.5-antix.1-486-smp root=UUID=b190a7bf-2813-42af-a303-564552a8407c ro 3
initrd /boot/initrd.img-3.9.5-antix.1-486-smp

title Debian GNU/Linux, kernel memtest86+
root (hd0,0)
kernel /boot/memtest86+.bin

### END DEBIAN AUTOMAGIC KERNELS LIST

I removed the 3.7 kernel, what should I change to display only the 3.9.5 in grub?

Comment out this part, closer to the top:
Or, since you removed it, just delete that bit...

#title antiX at sda1, kernel 3.7.10-antix.3-486-smp
#root (hd0,0)
#kernel /boot/vmlinuz-3.7.10-antix.3-486-smp root=/dev/sda1 quiet
#initrd /boot/initrd.img-3.7.10-antix.3-486-smp
#boot

???

yes

#boot also?

yep

thanks, it works!

good good! have fun with it.
From now on, when you install a new kernel, and update-grub, the new kernel will be on top of the list, closer to the bottom of the file, and be the one that boots by default.