Hey Michelle,
I absolutely LOVE this question, because it really dives into the theory that is behind TLCs. The idea is that the reason why things move far, or not so far in TLCs, is due to the H-bonding interactions that can occur between solvent/materials/plate. The plates used in TLCs generate hydrogen bonding and so, when things are present that has hydrogen bonding capabilities, it will drown out the ability of the silica plate to polar-bond to the material ran on the plate.
Let's look at the solvent now. By using methanol instead of the hexane/ether mixture, we are now providing PLENTY of hydrogen bonding in the solvent, as methanol has those -OH bonds that are great for hydrogen bonding. This drowns out the available hydrogen bonding partners from the silica plate that are available to hold on to the compound you are running up the plate to keep it lower, and so, it will help all components move further up the plate.
I hope that that's helpful. Please let me know if you have any more questions.
Cheers,
Molly